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Intake Manifold Dyno Test

November 10, 2007


We decided to do some intake manifold comparison testing on a 474ci engine running a set of our 290cfm CNC ported KRE D-port heads with 10.2 to 1 compression on 91 octane fuel with a 236/245 duration hyd. roller cam.

We gasket matched 6 intakes to the 1233 Felpro gasket, each intake was mocked up to make sure port alignment was correct and each intake had the water crossover removed. The purpose of this test was to see how each intake behaved in this particular engine combination.Other combo's can and will have different results but I felt this info would be interesting to our customers to look at and may be helpful in parts selection.

A water brake dyno like the SuperFlow 902 we used for our testing needs to be set to operate in a certain rpm range based off the torque the engine is producing. After some initial pulls and adjustments to the brake, we were starting our tests @ 4000 rpm and ending them at just about 5500rpm other than the Torker II, whose tests ended @ 5700rpm. We tried some tests starting @ 3500rpm but the brake was running out of water pressure at higher rpms so we had to make some adjustments and increase the starting rpm to 4000 which unfortunately doesn't give us the torque data below 4000 rpm.

We started with a stock iron intake running a Cliff's Q-jet. After some tuning, we ended up with 515hp @ 52-5300rpm and 575 lb/ft @ 4000 rpm. The next intake was another cast iron unit but with the CNC machined plenum copied from Cliff's personal intake. With some minor tuning we ended up with 527hp @ 5300rpm and 579 lb ft @ 4100rpm. At this point we felt the Q-jet was optimized as well as the timing which was set at 32 degrees so no more tuning changes were made. Multiple pulls were made with each intake to make sure the dyno test was valid and that the numbers were repeated more than once. We then bolted on a Crosswind intake and it produced 526hp @ 5300rpm and 584 lb ft @ 4100rpm. The next intake was the Edelbrock Performer RPM which produced 541hp @ 5400 rpm and 591 lb ft @ 4000 rpm.
We then installed a Tomahawk with a 1 inch blended spacer as previous testing has shown this intake to not perform very well without the spacer.
Also in previous tests, we have found the Tomahawk to perform considerally better with a Holley carburator than with a Q-Jet, while on a Performer RPM, the Q-jet will typically make more power than with the Holley.
Anyway, the results with the Tomahawk and the Q-jet were 521hp @ 5300rpm and 549 lb ft @4500 rpm. This concluded the testing with the Q-jet as the next intake the Torker II has a square bore plenum so we installed a 950HP Holley on top of it with a 1" open spacer for the last test. The Torker II didn't disappoint and produced 554hp @ 5500rpm and 584 lb ft @ 4500 rpm.

A couple things to note, in a previous intake comparison dyno test on a similar engine with a Tomahawk and a Torker II with a 950HP and 1 " spacer, the Tomahawk was within a few hp of the Torker II. Also, we didn't use any spacers on any of the intakes with the exception of the Tomahawk and the Torker II. So, some different results may be seen with spacers but we were trying to keep the tests simple.
So which intake is the best? Well, the Torker II is hard to beat especially with a 950HP sitting on top of it, but the stock dual planes as well as the Crosswind and the Performer RPM are very strong at lower rpms. Below the rpm's we were testing in and depending on the weight of the vehicle and the gearing etc, they may perform better in the car.
All in all I was pleased with the testing we did and hopefully you will find the information as interesting and valuable as I do. Let me know what you think or if you have any questions, then please drop me an e-mail at techsupport@sdperformance.com