intake for towing

[abyars]

This is my first FE.  This is the first engine I've had for towing heavy stuff.  I have a stock 390 in my 1970 F250.  This is a work truck I drive daily and use to tow a 6000# travel trailer.  It still has the stock 2bbl intake.  I have a Autolite 4100 (1.12 venturi) I want to install.  I want to the change the intake to an aluminum 4bbl.  I started to buy Jay's book but wasn't sure it would be of use for my application.  I want to build all the power I can below 3500 RPM.  What 4bbl aluminum intake would be of use to me?  I've been looking at the Edelbrock Streetmaster, Performer & Performer RPM.  The Blue Thunder looks nice but not sure the $$ are justifiable for my use.

Since I live in the South I was thinking of having the heat riser blocked off to.  Would that have any ill effects?  We have some occasional 20 degree weather here but not for long.  I run a 1" phenolic spacer now and that seems to have fixed my hot start problems (corn liquor boiling in the bowls after shutdown).

[RJP]

IMO the best manifold for towing, low rpm, torque, driveability, etc is the FoMoCo iron "S" manifold. If you absolutly need an aluminum manifold for your truck use the Edel. Performer manifold. It is prob. the closest manifold to the "S" as one can get and about 50 lbs lighter. I have a 2WD 69 F 250 -390/C6 with a unmodified Streetmaster, swapped to the iron "S" manifold and picked up about 1.5 MPG, better driveability and more low end torque/power. Both manifolds used the same 600 Holley so the results were not influenced by other part combos, just a simple manifold swap.

[TomP]

I don't agree, the Performer RPM is my choice and used that on my ramp truck. Has no heat crossover so winter warmup takes longer but it pulls fine down low RPM and makes for great top end. Mileage was great but that depends on other factors. It certainly didn't hurt mileage.

[Joe-JDC]

If you use the truck exclusively for towing/work duty that never goes over 4000 rpm or so, then I would use a Performer 390.  It will give you the best velocity at low rpms of any of those manifolds, and probably the best torque of any.  I have ported two recently, and I am seriously thinking of installing one on my CJ just to test it against a PI, RPM, Streetmaster, and Street Dominator.  Joe-JDC

[abyars]

Thanks guys.  I really want an aluminum for reduced weight.  I never turn the engine above 4000 for sure.  I found a good deal on a Streetmaster and was just curious.  I'll keep my eyes out for a used Performer or RPM

[chris401]

I had a Performer 390 but never used it. I can say it had small ports the would work well with the C8 heads you probably have. I did swap from a Street Master to a 66 S intake in my F250. I went from 11.5 to 14 mpg. The S intake did well for towing and drivability where the SM was weak below 2,200. You can usually pick up a S for $60 to $100 and a Performer 390 for $125 to $200.

[CaptCobrajet]

I'm with Joe here............nothing will do what you describe as well as the regular Performer 390.  I have one on a 390 1-Ton flatbed, and I'd do it many times over.  Weld up the heat risers in the manifold..........at least .250 thick.  It might take .010 on each side to make it flat again, but well worth the effort in mid-July.

[jayb]

+3 or +4 or whatever on the Performer 390 for your application - Jay

[abyars]

I'm much obliged to you all.  Thanks for sharing your experience and knowledge.

I'll hold out for a used Performer.

Anthony

[RJP]

If you use the truck exclusively for towing/work duty that never goes over 4000 rpm or so, then I would use a Performer 390.  It will give you the best velocity at low rpms of any of those manifolds, and probably the best torque of any. I have ported two recently, and I am seriously thinking of installing one on my CJ just to test it against a PI, RPM, Streetmaster, and Street Dominator.   Joe-JDC

Joe, if you do install the Performer on your CJ will you post your findings and a little info on what the manifold needed rubbing on? I remember a while back you got about 300 cfm from one Perf. and curious if you have improved on that. For years I ran a unmodified Perf. on my Q code 66 Galaxie daily driver and found it a little limp for that combo. That manifold was replaced with a C7-F police intercepter manifold and S-O-P evaluation was a worthwhile improvement.

[Joe-JDC]

Will do.  I bought a new Edelbrock Performer 390, and ported it for myself, and I was able to get the average flow up about 5cfm over the  used one that I reported on the forum.  I was able to get the ports balanced nearly perfect-- within a few cfm of each other.   The average PI intake in stock form averages in the low 280 cfm range(H), F (285) Sidewinder (300) RPM (335) SM (270s) SD (290) and a Perf 390 stock was puny in comparison, but up to 4000 rpm on a 390ci, it is still best in my opinion.  Joe-JDC

[Royce]

At the risk of being laughed out of here, I will offer this data

from 2500-3500 rpm an Edelbrock SP2P  made 20 to 30 more ft/lb of torque than a Performer.  This was on a 416 D3 head 8.5 compression with a 210@.050 cam

[My427stang]

I'll toss in my experience

I have not seen any of the low rpm intakes do better on anything other than a dyno. 

When put to work, other than flat towing, you are working between a shift point and a shift recovery point.  In theory, if you have more torque at the recovery rpm then the engine should be better.  However, if that intake loses power at the shift point, how much the average power drops depends on how far off those two peaks are.

So with that being said, I have seen better performance on 360/390 trucks using a 428PI or CJ manifold, SP2Ps lose too much on top, and Performers (at least out of the box) just seem to have been a pig on everything I used them on.  A PI or CJ is a nice manifold for a truck and balances torque and peaks when you need to pull a bit harder

My experience with RPM intakes is that they are soft down low and fussy to accurately jet at low load, part throttle RPM, I wouldnt recommend them for a 360/390 truck.

[cjshaker]

I respectfully agree with Ross here. I have seen Performers get pretty decent fuel mileage and be decent on highway cars, but I have never seen one work well on a truck. In my experience, factory Ford intakes always seem to perform very well. Whether it's a PI, a CJ or a stock S intake (which is what I have on my F-250), they have always seemed to work perfectly for non high performance trucks and cars where some power is needed or wanted at certain times, such as taking off and pulling with loads. A case where it's hard to beat the factory matched stuff.

[Drew Pojedinec]

Yeah, won't lie.
When I pulled the T intake off my truck and tossed on a Performer RPM I did feel like I lost a good bit of grunt right off the bat.  I did try my best to compensate for it, but it is what it is.
I just plain ole refused to put the iron intake back on   Clearly the solution is I need to build a 445 to make use of the intake