Centrifugal supercharger question

[My427stang]

Jay, or anyone else that has experimented with centrifugal superchargers, a few questions

- Is there boost at idle?
- Do you limit boost on the top end with any kind of waste gate or is it all determined by pulley speed?
- What is the max static compression you have run?

Thanks

[jayb]

Looking at blowers now, Ross?  Those things are great, and if you happen to pick a Vortech blower I can help you with the mounting and pulley arrangements, because I went through all that stuff with my supercharged engine.  Answers to your questions are as follows:

- On my setup there was no boost at idle; boost didn't start coming on until around 1500 RPM, and then really didn't hit until 2500+.  However, the engine cooling requirements at idle were substantially greater than with a naturally aspirated engine.  I would guess this is because the blower heats up the induction air so much, and also because of the greater load on the engine to turn the supercharger.

- I was always looking for more boost, so I did not limit it at the top end.  Most people will just change pulley sizes to set the top end boost value.  I was able to get 17 pounds out of my Vortech V7 Ysi supercharger, with the HTD belt drive.  With the 10 rib belt, the supercharger would only deliver 11 psi due to belt slip.  So that is another way to limit the boost 

- Since I was going for big boost, and had a carburetor, I held my CR to 8.75:1.  If I decided to switch to EFI, I may have gone higher...

Hope that helps - Jay

[plovett]

That's interesting because I've read that you can actually run more boost/compression with a carburetor than with fuel injection.  Even ATI says that.  I don't know personally because I've never tried it back to back.   I've never even run a supercharger.   I do think centrifugal blowers are especially cool for a street/strip car.   More efficient than a positive displacement blower and less heat than a turbo, probably (maybe?) better mileage than a naturually aspirated 550-600 cube monster, plus the incremental boost seems ideal for a traction limited scenario.

I loved reading about the blown Mach I, Jay!  I'd like to run a blower myself someday.   I hope this thread keeps going.

paulie

[My427stang]

It wont be for a bit, my engine is currently 10.7:1 and although its a stable block, its a .047 over center oiler, I'd like to reblock at the same time I drop the compression, plus I need to spend my free time wrapping up the truck

That being said, in a pretty good place right now and considering selling my Harley due lack of use, so my timeline could be pretty quick if I decided it to be

To be honest a secondary plan was to buy a used Viper and hang a huffer off it, but that just seems frivolous.  A blown 505 inch EFI FE seems much more conservative

[fe66comet]

The main concern is always what you put under the top end. A 390 for instance will not hold up to big boost. Start off with a cross bolted heavy web block, forged crank and H beam rods. That is anything over 6 or 7 psi and 600 HP is pushing the limit. After that a 428 with after market caps and studs.

[My427stang]

Mine is a 489 inch .047 over 427, H beam rods, lightened SCAT crank, Diamond pistons.  Despite being a seasoned and trued 427 block that I have owned and ran for a long time, I just don't think it'll love living above 700 hp.

It'd probably make it, but if it didn't what a mess

[plovett]

You considered putting some Hardblock in that .047 over 427 Ross?   Sounds like you're planning an aftermarket block for your blower build which would of course be even better.  Expensive though.   

A blown Viper would be fast, but they sure sound funny.   

paulie

[My427stang]

I am not a hard block fan on the street, at least not the way I use the car. 

The reason I was asking the questions I did is because I am attempting to keep torque up at very low RPM cruise too.  Although I wouldn't build a fresh one with high compression purposely, I did wonder how 489-505 inches would behave in 5th gear at 1800 rpm with 8.75:1 and a little more cam vs the current 10.7:1 and a relatively mild cam.  Having boost down low should offset that

That of course made me wonder, what if I had no or little boost down low, but could control it up top enough to run the compression I have?  Of course I looked all over the net and haven't seen ANYONE recommending that much compression, so my guess is that the cost offsets the gain with only 6-8 psi of boost

[My427stang]

Well I did find this link this AM

http://www.blowerdriveservice.com/techcharts.php

It would lead me to believe that somewhere around 2-4 PSI is about all it would handle with the current compression LOL 

For the cost of a blower, the gain of 2 psi would certainly be deeply into stupid poser status 

I just need to finish up the truck and get planning on a big one.  Maybe do some swapping around and put the 489 in the pickup, sell the fresh 445 after the summer, and start from scratch

[falcon428]

Yes but the "stupid poser status" is so popular in my area.  :-).  Most of those cars around here are left-overs from the "Pro Street days".

[jayb]

That's interesting because I've read that you can actually run more boost/compression with a carburetor than with fuel injection.  Even ATI says that.  I don't know personally because I've never tried it back to back.   I've never even run a supercharger.   I do think centrifugal blowers are especially cool for a street/strip car.   More efficient than a positive displacement blower and less heat than a turbo, probably (maybe?) better mileage than a naturually aspirated 550-600 cube monster, plus the incremental boost seems ideal for a traction limited scenario.

I loved reading about the blown Mach I, Jay!  I'd like to run a blower myself someday.   I hope this thread keeps going.

paulie

Well, that's interesting Paulie, I would have never guessed that.  My theory that you can run more compression on a supercharged application with EFI is that you would have better cylinder to cylinder fuel distribution than you would with a carb, and so the possibility of leaning out one cylinder and detonating is much reduced.  I also thought that I read somewhere that some of the more recent factory supercharged offerings are running up at 10.5:1, or maybe it was a Mustang race class, and this was also with EFI.  The only thing I can think of that would be an advantage for a carb setup is that the fuel would have more time to cool the charge, compared to EFI.  But since I've never run that kind of compression with a blower, I can't say it won't work with a carb...

[jayb]

Yes but the "stupid poser status" is so popular in my area.  :-).  Most of those cars around here are left-overs from the "Pro Street days".

LMAO at "stupid poser status"!  We get the Car Craft Summernationals every year in Minneapolis, and there is a LOT of that going around...

[plovett]

I am not a hard block fan on the street, at least not the way I use the car. 

The reason I was asking the questions I did is because I am attempting to keep torque up at very low RPM cruise too.  Although I wouldn't build a fresh one with high compression purposely, I did wonder how 489-505 inches would behave in 5th gear at 1800 rpm with 8.75:1 and a little more cam vs the current 10.7:1 and a relatively mild cam.  Having boost down low should offset that

That of course made me wonder, what if I had no or little boost down low, but could control it up top enough to run the compression I have?  Of course I looked all over the net and haven't seen ANYONE recommending that much compression, so my guess is that the cost offsets the gain with only 6-8 psi of boost

Now I think I understand where you're coming from.   I don't think you can do what you want with the current compression ratio. 

You ever read about the old Mcculloch variable ratio superchargers?  They had a variable speed pulley set up.   They had a higher ratio at low rpm for more low rpm boost.  At higher rpms the ratio was lower to keep the boost from going too high.  I don't know exactly how it worked.  It seems like it was an arrangement of springs working against centrifugal force (inertia) and oil pressure.  Paxton later had a variable speed supercharger with the ratio change made internally in the supercharger.  Something about moving the planetary balls around for different contact points???   Hee hee.

I realize this stuff isn't helpful.  Just shooting the shite so to speak.   Old airplane engines often had multiple speed superchargers as well.  They would have lower ratio for use at low altitude to avoid overboosting the engine, then at a certain higher altitude they would shift into another gear to run the supercharger faster  to maintain similar boost.  The Germans even used a hydraulic coupling to the supercharger to make continuously variable ratio.   These were all centrifugal blowers, though turbos were sometimes used to feed the centrifugal blower.   Like I said probably not helpful.   

If you want boost at very low rpm it seems like a turbo might be better as it's boost is more load sensitive than rpm sensitive.  You could dump the "excess" boost at high rpm without the huge power loss of turning a mechanically driven blower.  Maybe? Or if you're using fuel injection then maybe a helical screw blower might be low enough in height to fit under a scoop.

Or maybe just use very large displacement motor like a 572-604 with 385 series architecture.
 
paulie

[plovett]

Well, that's interesting Paulie, I would have never guessed that.  My theory that you can run more compression on a supercharged application with EFI is that you would have better cylinder to cylinder fuel distribution than you would with a carb, and so the possibility of leaning out one cylinder and detonating is much reduced.  I also thought that I read somewhere that some of the more recent factory supercharged offerings are running up at 10.5:1, or maybe it was a Mustang race class, and this was also with EFI.  The only thing I can think of that would be an advantage for a carb setup is that the fuel would have more time to cool the charge, compared to EFI.  But since I've never run that kind of compression with a blower, I can't say it won't work with a carb...

Yes, I believe it's a heat of vaporization deal with the carb having more distance/time to cool the charge.   I don't know if modern supercharged cars run a lot higher compression with EFI.   The naturally aspirated cars sure do though.   

Ponder this.  Would those methanol/water charge coolers be as effective if they were injecting at the cylinder head?  I dunno.

paulie

[fe66comet]

Really most superchargers are happy at a 5000 rpm limit anyhow. They become inefficient after that and turbocharged becomes a better choice.

[plovett]

I don't know if I agree with that.  The supercharger speed is determined by the pulley ratios and the drive ratios in the supercharger itself.   So a supercharger could be turning any number of speeds when the engine is at 5000 rpm.   And many engines turning 7000+ rpm use centrifugal blowers.   The max impellor rpm can be very high.

http://www.procharger.com/models.shtml

JMO,

paulie

[jayb]

Centrifugal superchargers run at speeds much higher than 5000 RPM, more like 30,000 - 40,000 RPM.  Roots superchargers run much slower, if I recall correctly...

[plovett]

Here's a more doable idea IMO, Ross.  Convert your 489 to run on E85.  That ought to work with your compression ratio and a blower.  I don't know exactly how much boost you could run.  I think it might work with moderate levels like 7-9 psi. 

paulie

[My427stang]

I could Paulie, but with me moving around the country pretty regularly, I am not sure of availability everywhere

Here in the midwest there are pumps everywhere, but I dont remember it being that accessible in MD or VA and my next move is likely DC

I think when the truck is done I'll just build what needs to be built, maybe sell off the 489 to minimize shit build up in the garage, or like I said earlier, put it in the truck and sell the 445.

We'll see how it evolves, definitely doing something though, itching to take it to the next level

[plovett]

Just throwing out my opinion here.  I don't think your 489 is good combo for a truck.  Mostly because of the compression and cam.   The cam is fairly small for a motor that big and the compression is fairly high for a truck.   I say the cam is fairly small, but in a truck I think I'd want something even smaller.   But then that would exacerbate the high compression.  So you're kind of stuck in my opinion.   It'd be nice truck combo if you could put some good big chamber heads on your short block.   I'm not sure what heads those would be though.   That or keep the current heads and "partial-rebuild" the bottom end with different pistons and a smaller cam.

All that said, I'm sure your current 489 would still work in the truck mostly just because it's a big motor.  It'd still go like stink and I know you're smart enough not to floor it in top gear at 20 mph, going uphill, with a load in the back, in July, with 87 octane in it.

JMO,

paulie

[My427stang]

The truck is only 4100 lbs, it'd be absolutely fine, it's a tight quench motor, 8.33 DCR and too many hours of head and piston surface work that will run on any swill out there and is perfectly happy at 1600 rpm chugging along.

Basically, consider it a Galaxie with a 4 speed and a 286 adv duration cam and 10.7:1 in a truck's clothing

Keep in mind, I drive a Superduty and it does any of the work, the truck is a hot rod and has been used that way since the 90s, to include a stretch with dual nitrous bottles bolted to the roll bar and a Predator under the hood...  Driving hard is not a new concept for this old beast

I actually consider the current 445 very undercammed, which I have been teased about a bit by my local buddies

[plovett]

I guess I was thinking it was truck like a "truck".  If it's a hotrod then put the small cammed 489 in there.  What's  the deal with putting small cam's in everything you build???

paulie

[My427stang]

Thats funny, but I do have an explanation followed by a silly reason on the truck

1 - I spend far more on heads, intake and headers than on anything else.  I think power is made in those areas and the right cam complements those.  A big cam with crappy heads is just a noise maker

2 - After I plan that, I cam to the intended use based on those parts and some gut feeling, and in my case, the Mustang needed to be able to handle a 2.36 final drive happily, ended up I geared it lower and went with a 2.63 final.  So yes its a bit small, but with all the head work it'll pull hard to 6500 shift point, but likes 5th gear at 40 mph

Small is of course relative too, the cam card reads 242/248 @ .050, .595 lift and it's designed to run at .026 lash, I run it at .014, so its a little more than the cam card would indicate

Its not really in that order, it all happens at once, but I really like a deep breathing head over a lumpy cam if given the choice.  Admittedly, the EFI dropped idle by 200 rpm and increased torque significantly, so I probably could handle a little more cam now.

Now for the truck...all that "proper planning"  is blown out the window

1 - I didnt want to have to break in a new cam
2 - I didn't want to spend money on adjustable valvetrain, all I did was add end stands
3 - The 270H was in it already and had very low miles
4 - Rocking it back to 110 ICL got DCR around to 8.2 and theoretically kicked the rpm range a bit higher
5 - Ported the hell out of the heads and intake to hopefully keep the baby cam's hp peak near 5200

So we'll see how this backwards experiment goes, to be honest, I think the truck would love a 282S on a 105 ICL, but it's together and sounds real nice. We'll see if it hits a wall at 4500 LOL

[plovett]

Fair enough.  I especially agree on your point regarding heads, intake, and exhaust first.  You can still have a lumpy cam after that if it makes sense.   It's not like you have to choose one or the other, but not both.  Still,  those things you mentioned should come first.   What a hotrod is to me is not exactly what it is to you and I shouldn't project my proclivities onto you.  There.   

So,  what is the general plan for the 'Stang then?   A 500+ inch FE with BT heads, twin throttle bodies,  FI, cammed for a wide rpm range with killer low rpm power?

paulie

[My427stang]

I think we probably have a little different ideas, but don't underestimate a 489 inch FE with heads that flow in the 320s, 3 inch exhaust, 10.7:1, a ported Victor, a 1200 cfm throttle body and 4.11s.  It's no Lexus

Remember, I drove this car up and down the west coast with 4.10s, all insulation removed with a 433, 250@.050 Isky, a Portosonic, Flowmasters, no a/c and a 4 speed, those days are long over for me!

Next one will probably be a 505 with a wide LSA hyd roller and a blower, max rpm 6500-ish??.  Still working it out, I have a bit of turbo time, but never built a blower motor so need to do a lot more research.  Regardless of the build, it needs to be able to happily do a 5 or 10 hour drive and idle in any traffic, regardless of the build.

To be honest, my driving style might like a turbo better, but I am not sure the car has the room for the piping I'd need for that big of a motor and I hate to add heat under the hood

Jay, to get back on the topic though, do you shoot for a different DCR number or consider a max overlap number when you run a blower?  I would think that overlap is less important at midrange and could waste boost on top.  I also assume normal DCR numbers sort of go out the window

[plovett]

Well, that ought to do the trick.   I really want to use a centrifugal blower myself someday.   I'm keeping one of my 391 cranks with the big snout (and have a 391 timing cover)  in case that proves helpful if I ever run big boost.

Any ideas on the heads?   For years people used to say if you put a blower on it the heads don't matter to much, 'cause the blower will force the air through there regardless.   I've always had the opposite belief.   I think if you're flowing more air the head is becoming a bigger restriction, not a lesser one.    The crappier head may produce bigger boost numbers and less power.   

Intercooled?   I like the idea of air/air intercoolers though you have to find a place for them.   In front of the radiator, or possibly in one of the wheel wells?   

Victor intake?

Cogged drive belts are nice for a blower, IMO. 

paulie

[My427stang]

Paulie, I'll probably run the heads I have now.  I agree that eventually they become a restriction, even with a blower, but I won't get any serious gains from what I have without ridiculous money.  With the boost and RPM I plan to run, I don't think I need a whole lot more

As far as an intercooler, I do plan to run one

[jayb]

When I was doing my blower engine I had the good fortune to stumble across a Ford engineer with a lot of experience in that area.  His official title was "Senior R&D Engineer, Boosted Engine Projects" or something like that.  At the time he was working on a race program with one of the 10.5 Mustang classes, and had some contacts at Vortech that helped me out quite a bit.  Anyway, what I learned from him were a few general rules, such as:

- Anything you do to the heads, intake, exhaust or cam that will help a naturally aspirated engine will also help a boosted engine.  The old saw about not needing to do headwork because of the blower is not correct.  Headwork and other induction system work, including a big cam, will help a blower motor just like it helps a naturally aspirated engine.

- Shoot for the widest lobe separation angle that you can, within the limits of the cam specs that you want to use.  I used 116 for my supercharged engine, and the cams for my SOHC turbo motor are also 116.

- You may actually want less exhaust duration on the cam with a turbo motor, rather than more.  This is counterintuitive, but has something to do with the way the exhaust pulse helps spool the turbo.  My turbo SOHC cams are the same cams as the ones in my 585" SOHC, but with about 6 degrees less exhaust duration.  This doesn't necessarily apply to a supercharged motor, though.

Also, I ignored DCR on my blower motors, because it was so low due to the static compression ratio and big cams.  I'm not sure that the same rationale applies to a blower motor anyway; you are packing more air molecules into the cylinder with a blower, so from a fairly simplistic perspective DCR would go up with boost.  I don't know how to calculate that; my Ford engineer friend told me that the formulas for calculating actual compression ratio from static compression ratio and boost pressure are not really accurate.  (At 15 psi of boost, you are packing twice as many air molecules into the cylinder.  This is not the same as doubling the static compression ratio.)

On other thing that I found very interesting on my supercharged engine was that it made more power with the Performer RPM intake than it did with the Victor.  My motor was carbed, and this may have had something to do with it, but I'm not really sure.  You could really see this in the exhaust temps on the dyno; the Performer RPM had exhaust temps that all wanted to converge at higher engine speeds, while the Victor's exhaust temps diverged.  I assume that this was due to better fuel distribution in the Performer RPM intake than the Victor.  If you went with EFI, I also assume that this would no longer be an issue, and in fact I have a Victor that I got from Barry R that is heavily worked over, and was planning on going to an EFI setup on the supercharged engine at some point...

[plovett]

I agree that eventually they become a restriction, even with a blower,

I'm going to reiterate this.  I'm not trying to hassle you or anything.   It's just I don't think I'm getting my point across well.  You said the heads may become a restriction even with a blower.   I think a blown motor needs more cylinder head to work well.   That's what I meant when I mentioned the old school thinking about blowers and cylinder heads in my previous post.  Is a head that is right for a naturally aspirated 489 also right for a blown 505?   Sure it'll make a whole lot of power with the blower, but you're still trying to stuff a lot more air through the same space in the same time.  You're actually working the port harder.   The harder you work the port the less power you'll make (compared to a bigger better flowing head) and the more you'll heat the charge (you'll have a higher boost number, too).   Sure the intercooler will remove some of that heat again, but then you're really working at it the wrong way, IMO. 

I agree with Jay's point that anything that helps the naturally aspirated motor make power will also help the blown motor.  I would go a step further.   I think the gains are proportional, maybe not exactly directly proportional, but proportional nonetheless.  Say if you gain 50hp with a head swap on a naturally aspirated motor, you might 75 hp or more if you did the same head swap on a blown motor.

For sure don't take my word for it.  Ask the experts.  I'd look at the heads before I bought that big cube short block and the blower to put on it.

JMO,

paulie

[My427stang]

I got it Paulie, but I am not sure I agree completely, but I certainly do in spirit

To oversimplify, you need enough head flow to not back up the port with the volume of air going through, no more.

What a head flows under vacuum does not mean it will flow too little with pressure, and it doesn't mean that it still wont be very effective at different levels of boost even if it falls off at high levels

I agree there will be more gains with a larger port at higher boost levels, but the principals still apply.  A big lazy port at 1500 rpm where there is no boost, is still a big lazy port at 1500 rpm

But I do understand your point and I agree, my words would be that "the more air you push through a port by any means makes port design even more critical to get the most you can out of the engine"

[plovett]

Okay.  We're on the same page, basically.

To oversimplify, you need enough head flow to not back up the port with the volume of air going through, no more.

How would you know when you have too much flow and are "backing up the port"?  And what does that mean in physical terms.  Does pressure/turbulence go up in the port as the air can't be exhausted as fast as it's coming in?  I don't know how you'd measure that or know it's happening unless it was related to a power drop off.  And then you wouldn't know it unless you compared to a different head on the dyno.  Does it happen at a specific point or gradually?  I'd venture gradually.  If so it's not like a yes/no thing.   

One other thing.  Sure with a blower the port is under pressure as opposed to vacuum, but there is really no fundamental difference.  It's the difference in pressure that we call a vacuum or boost.   A blower just creates a greater difference in pressure.   So it's not like the physics have fundamentally changed just because you have a blower.  It's still the same deal and the head has to deal with it.

As an aside:  Have you considered cutting open the "cheek scoops" on your '70 Mustang?  You could have ducting on one side leading up through the fenderwell to the intake of the supercharger, right by the shock tower.  On the other side you could have ducting leading to an air/air intercooler placed in the fenderwell.   Just a thought.   I think it'd be cool.

paulie

[plovett]

A big lazy port at 1500 rpm where there is no boost, is still a big lazy port at 1500 rpm

I think that's something I can't refute.   Are you really looking for power at that low of an rpm?  If so it seems like a larger engine or postively boosted engine might be in order.  Maybe.

paulie

[cdmbill2]

Air to air intercoolers want the largest surface area possible much like radiators so a small duct from the 70's front fake scoop would be enough until very high speed. I've been looking into water to air like the current Shelby's or the Lightning/HD trucks like the one I have. The packaging can work better as the heat exchanger can be low mounted while still leaving plenty of direct air flow to the radiator.

Better heads equal more power with less 'boost' as the pressure is a measure of restriction in the inlet tract, not a measure of how much air/fuel has been crammed into the combustion chamber. The better heads also allow for a slightly smaller cam, but an aggressive lobe will out perform a more gentle one with the same measured duration and lift.

[My427stang]

How would you know when you have too much flow and are "backing up the port"?  And what does that mean in physical terms.  Does pressure/turbulence go up in the port as the air can't be exhausted as fast as it's coming in?  I don't know how you'd measure that or know it's happening unless it was related to a power drop off.  And then you wouldn't know it unless you compared to a different head on the dyno.  Does it happen at a specific point or gradually?  I'd venture gradually.  If so it's not like a yes/no thing.   

One other thing.  Sure with a blower the port is under pressure as opposed to vacuum, but there is really no fundamental difference.  It's the difference in pressure that we call a vacuum or boost.   A blower just creates a greater difference in pressure.   So it's not like the physics have fundamentally changed just because you have a blower.  It's still the same deal and the head has to deal with it.

As an aside:  Have you considered cutting open the "cheek scoops" on your '70 Mustang?  You could have ducting on one side leading up through the fenderwell to the intake of the supercharger, right by the shock tower.  On the other side you could have ducting leading to an air/air intercooler placed in the fenderwell.   Just a thought.   I think it'd be cool.

paulie

You got it Paulie.  As far as when a port can't flow enough, I haven't done it, but I understand when boost climbs but power doesn't or only does at a small rate, it's because the port is backed up.  At that point you are building pressure in the plenum that can't get into the cylinder.

I have seen it on a SBF test in the rags, but not an expert on when that happens and still researching how to determine port CSA and overall flow for a boosted street engine

In terms of the intercooler, I haven't though too much about it, but I think I would like a larger intercooler than the cheek would allow.   So my thought now is to feed air in from the scoop area and have a big intercooler across the front, below the bumper like a modern diesel.

As far as where to make power, I don't need big power at 1500 rpm, but I do want to make sure it doesn't buck and can lump along between 1600-1800.   It does so very happily now, especially with the EFI, it was good before but not as good with the 1000 Holley and RPM intake.  The EFI was certainly magic, even with a ported Victor and less lash, it idles much lower and I can loaf along or spin 6500.  I was the blown motor to do the same

So the point of going bigger motor, heck it does it now, and I want to be able to do it with a 505. so I don't see how that will be a problem at all

[plovett]

Sounds like you have it all figured out already, Bro.  I'm sure it'll be a beast.

paulie

[My427stang]

I sure wouldn't say I have it figured out, but I do know how I want to run the pipe LOL

My guess is there will be lot of learning coming my way for blower and cam choices, not to mention EFI programming under boost.

[jayb]

I think the EFI stuff will be easy, Ross.  You'll just need a 2 bar or 3 bar MAP sensor, and big enough injectors to feed the horsepower level you are expecting to make. 

The big questions will be which blower to get, and what cam to run.  And actually, the first big question will be how much horsepower do you want to make?  That will drive a lot of the other choices.

Have you picked out a blower?

[My427stang]

I have not yet Jay, looking for something that will mount on the pass side and fit a low mount alternator.

That will let me keep PS and A/C on the other side.   I think I am going to have to do some work on the radiator support to make some room, I am pretty much out of room with a shroud and cant imagine fitting a big belt in there

[plovett]

Air to air intercoolers want the largest surface area possible much like radiators so a small duct from the 70's front fake scoop would be enough until very high speed. I've been looking into water to air like the current Shelby's or the Lightning/HD trucks like the one I have. The packaging can work better as the heat exchanger can be low mounted while still leaving plenty of direct air flow to the radiator.

Better heads equal more power with less 'boost' as the pressure is a measure of restriction in the inlet tract, not a measure of how much air/fuel has been crammed into the combustion chamber. The better heads also allow for a slightly smaller cam, but an aggressive lobe will out perform a more gentle one with the same measured duration and lift.

I agree the fenderwell is not the ideal location in terms of large space and airflow.   I try not to mount heat exchangers if front of my radiator though.  Still, in front of the radiator is probably just about the only space for a large air/air intercooler.   ATI makes some intercoolers that are 9"x4.5"x11" that would fit in my fender.   You'd have to make some ductwork and maybe a shield to protect from it road debris.    And whether it has enough cooling capacity would be a question that depends on the build particulars.

paulie

[sumfoo1]

i have a 482 stroker pond block setup with pond heads at 9.5 to 1 forged crank oliver rodded bottom end. i was thinking about turboing her at some point  but i'm pretty sure my 112 lsa 262@.050 cam may be a little much.

its gonna be in a 61 galaxie so i have plenty of room for a giant air to air intercooler

its an efi engine using the victor efi setup.

i'd like to run 6-9 psi on pump and twice that on some kind of race gas or e85.

sound feasible or?? overzealous?

[jayb]

I think you might have too much compression to run that much boost, but you might be able to get away with it using EFI and timing control. If the engine is already together you can certainly give it a try, and the intercooler and maybe a boost cooler setup will help.  If you just can't get to the boost level you want, you can always change pistons.

Why do you think your cam is too big?  The only thing I would say about the cam is that it could use a little more lobe separation, maybe 114 instead of 112.  I ran 17 psi in my 489" FE with a Vortech supercharger, and my cam was bigger than yours (272@.050" I think?).  Compression ratio was 8.75:1.  Made a little over 1000 HP on race gas with a carb; probably would have done better with EFI like your setup...

[sumfoo1]

question... thicker head gaskets a bad idea... i think going from .030 to .080 on the head gasket (doing something like SCE pro copper or something) can get me down to 8.72/1 CR but is it a bad way to do it because i'm effing up quench? or is it really not going to affect it much?

My issue is all my tuning efi experience is on a Subaru lol  so i'm a little used to some help with knock sensors but usually my ears can pick out an unhappy engine before the knock sensor does. I will have timing control too  i'm pretty sure it goes similar to the subie...  lots down low tapering to barely any advance when she first hits full boost and then start feeding it back in. 

[jayb]

The thicker head gaskets are kind of a double edged sword, in my opinion.  Lowering the compression ratio for your application is good; increasing the quench distance is not good.  On the other hand, some engines (like the SOHC) don't have any quench at all.  If you can change the head gaskets when you go to the turbos, I think I would opt to go to thicker head gaskets.  You might look at getting some thick Cometics rather than copper gaskets; they'll last longer, and I believe that they are available in multiple thicknesses for the FE.

When you get around to doing this, I would STRONGLY suggest you set the engine up and tune it on a dyno.  You can sneak up on the tune that way and avoid potentially damaging scenarios.  You can blow a supercharged or turbocharged engine real quick with the wrong timing or air/fuel ratio...

[sumfoo1]

yeah... it will be tuned by a local shop that tunes for a couple ford x275 cars.

I did my own with the subie (23psi @ 10.8-11.2 afr & 373whp 405ft-lbs on a 2.5liter with crazy amount of drivetrain loss [awd] and more impressively 40k miles on a stock bottom end with this tune) but this engine just costs too much money not to let a pro do it.

the pump tune will be WAY mild and i'll tweak it to fill in gaps/hole  myself but the race gas tune will be on someone who knows how to trim out the fat safely

i mean i know i can the heads to do the turbo setup i guess i could just as easily pull the pistons as change head gasket.. i'm just one of those people who lets everything snowball so i'm trying to keep round 2 reasonable.

i was going to do a mild refresh on my 352 when i ended up with the solid roller 482 with 4 bolt aluminum block yadda yadda yadda
its a disease i swear.

[jayb]

i was going to do a mild refresh on my 352 when i ended up with the solid roller 482 with 4 bolt aluminum block yadda yadda yadda its a disease i swear.

Sounds familiar 

[Qikbbstang]

cheapy and a full house high dollar model... Cost difference if I recall was well over $3000 and the power output and boost was as wacky as the price difference.