I have a couple articles with the "FIRST" in them that I saved from rags back in the late 80s and early 90s. I need to scan them.

The info Gregg gave earlier on the "400 - horse" engine is the most powerful engine it was used on.

This is one of the lower HP applications from a May 1989 Car Craft (some else’s scan).



The test engine was a stock 1988 Corvette L98 with the old Edelbrock 1.5" / 1.625" headers running through an F-body dual cat exhaust system.

The baseline was a totally stock TPI unit with a stock MAF, chip, and set at 6 degrees

The AS&M set up is a hand ported stock base with their AS&M runners and ported plenum using a stock MAF, chip, and set at 6 degrees

SLP brought a prototype intake called the ShortRam that never made it to production. It looks VERY much like the Holley StealthRam and they brought a custom chip to use for testing but used the stock MAF.

TPiS used the "Big Mouth" intake, their Semi-Siamesed runners, an air foil, and a modified MAF sensor, stock chip,,, set at 6 degrees.

Air Sensors, FIRST used it's single mono blade throttle body,,, which should flow around 800 cfm,, it's own fueling electronics, and 4" MAF sensor with a mechanical advanced distributor set at 6 degrees. So,,, it’s hard to say exactly how much their “tune” helped or hurt the numbers shown.

I have another article where they tested a number of intakes on a “350 horse” engine,, if I can get some time this weekend I’ll scan it. The thing is,, while the intake does well on these lower HP applications,,, where it's going to seperate itself from the pack is in the fully ported applications to take full advantage of the more than capable cross-sectional area.

 

"where it's going to seperate itself from the pack is in the fully ported applications to take full advantage of the more than capable cross-sectional area"

Exactly right, plus the available harmonic wave tuning which is not to be sneezed at.

 

BADSS:

In the CarCraft scan posted above, the FIRST intake peaks at 3500rpm. However, with the information I posted on the prior page, it peaked higher than that. (Notice torque was 460 vs 443 when it went from 3500 to 4k rpms).

Got any theories on that?

 

Here’s the earlier info referenced:

9:1 355 AFR heads hydraulic cam
RPM - FIRST - MiniRam - AZ Speed & Marine
2500 - 175 ---- 175 ----- 180
3000 - 237 ---- 222 ----- 238
3500 - 295 ---- 263 ----- 295
4000 - 350 ---- 300 ----- 325
4500 - 377 ---- 350 ----- 352
5000 - 388 ---- 375 ----- 350
5500 - 366 ---- 398 ----- 330

The FIRST made 443 TQ vs the Miniram's 395 TQ at 3500 rpm (+48)
The FIRST made 460 TQ vs the Miniram's 394 TQ at 4000 rpm (+66).
------------------
If you calculate TQ at 4500,, this is the peak TQ for the MiniRam in the 500 increments listed

The FIRST made 440 TQ vs the Miniram's 408 TQ at 4500 rpm (+32).


Here’s the stock L98 torque – SLP “proto-type” is similar to the StealthRam

RPM - FIRST –“Proto”- AZ Speed & Marine
2500 - 312 ---- 295 ----- 315
3000 - 339 ---- 303 ----- 347
3500 - 353 ---- 317 ----- 358
4000 - 339 ---- 319 ----- 343
4500 - 321 ---- 312 ----- 314
5000 - 277 ---- 286 ----- 262

Since both “charts” are in 500 RPM increments, you don’t know exactly where the engine’s peaks are, but should have a fairly good idea.

In the top graph, you’re dealing with a more powerful engine using AFR heads with a larger cross-sectional area and a cam that is larger than stock,, so peak torque will automatically be higher than stock heads and cam as long as the intake can support the larger cross-sectional area. Peak TQ for the MiniRam would be between 4000 and 4500,, with a lean towards 4500. Peak TQ for the FIRST would be right about the 4000rpm mark,, or approximately 500 rpms less than the MiniRam.

In the bottom graph, you’re dealing with a less powerful engine using stock heads with a smaller cross-sectional area and a stock cam,, so peak torque will happen at a lower RPM. Again,, with 500rpm increments, best guess for peak TQ with the Short Runner “Proto-type” would be around 4000rpm. Peak TQ for the FIRST would be right about the 3500rpm mark,, or approximately 500 rpms less than the short runner intake.

Now.. just because both examples show a 500rpm difference between torque peaks doesn’t mean there will always be a 500rpm difference between peaks with these two intakes on every combination. However,,, the longer runners will always produce peak torque at a lower RPM due to the midrange inertia and harmonic boost – there’s just more torque in that range. As long as the long runner intake’s cross-sectional area is up to task with the heads,, it’ll try and produce the native torque curve (like a short runner / untuned intake will do) past it’s runner length’s tuned range,,,, and torque won’t start dropping off from the shorter runner’s torque curve until the cross-sectional area and pumping loss from the length of the runners start having a negative effect on upper rpm power. If you get the cross-sectional area large enough,, there’s not going to be a huge drop off in upper rpm power like you see with a stock TPI either.

For example, the FIRST in the first chart still had 31.5lb/ft on the MiniRam right about the MiniRam’s torque peak of 4500,,, and still made more torque at 5000 rpm. As the diameter and length of the runners come into play, combined with the rest of the engine combination,,, the power starts to drop off. These are the older lesser flowing AFR heads with a decent sized cam,, still I feel confident that the FIRST had little if any porting or work done to it. If it had been opened up more, you would trade off a little less TQ in the lower RPM range to enable it to better match the native torque curve of the engine and produce more HP at a higher RPM. The cool thing about the FIRST is that on a large majority of engines, given the effort in porting and siamesing,,, it gives you one more way to truly dial in a combination’s power band previously not thought available before.

 

I just received a new engine simulator program called DynoSim5. It is a big upgrade to their old DynoSim program and appears to be a lot more realistic than the older program. On DynoSim I automatically took off 5% from the totals.

Anyways one of the intake models is max flow long tube runners. It is based on the Porsche 928 intake system which is very, very similiar to TPI in concept. I think this would model the First quite well. Bottom line is I was very surprised by the numbers it spit out for my new motor using the long tube max flow model. Obviously they must be figuring on the 2nd harmonic wave being present. The numbers were very promising and I don't want to jinks things by posting them.

I also modeled the FAST hi-slow LSX intake on my motor and this one beat it out. I will say the max slow long tube runner is in between a hi-flow single plain and a tunnel ram horsepower wise. In a way I can see that.