BadSS

Yep, a picture can be worth a 1,000 words. The inside diameter of the unported FIRST runners are 1.75” and probably wouldn’t require much if any porting on most builds. However, the casting is VERY thick and can be opened up a good bit if needed. Here’s a comparison of a FIRST runner ported to a 1.92” INSIDE diameter up against the stock TPI runner.


Here’s a picture of a stock base on top of the FIRST, which has a 1.85” inside diameter as cast. The bottom picture shows the much superior runner to base and base to head transitions. Note the entrance and exit angles (or lack thereof) – this is a big reason why the FIRST works so much better than a ported (unwelded) GM style aftermarket base.


Another cool thing about the FIRST is even the aftermarket bases have trouble opening up to a 1206 gasket, but the base flange of the FIRST has enough meat that it could be ported as large as a 1207 gasket if needed. I think the FIRST is well worth the money if you’re looking for a long runner intake system.

While not “on the fly” self-tuning, I ended up picking the Dynamic EFI EBL P4 Flash System which uses a modified GM ECM and the stock GM harness. It’s more than sufficient for my needs and it’s “only” $470 if you send them your ECM. It does have VE Learn capability that with a wideband can even “learn” WOT. It does this in data logger mode, but it captures the “recommended” adjustments and allows you to “flash” the tune in a matter of minutes without removing the laptop from the car (no chips to burn). I haven’t used this one yet, but I doubt any of the “self tuning”, included these with the “recommended” tunes would be 100% accurate, but I do believe it will help get you where you need to be a lot quicker.

aklim

Don't know about your car but my hood is closed 99% of the time. As they say, out of sight, out of mind. In reality, I could care less if it looks like a turd if it can run like a raped ape.

aklim

I'll bite. How often do you make a tuning change? I suppose if you change it often enough that you think it is necessary to study up and practice it could be right. I have had 4 tunes since 91. Twice by Lingenfelter, Twice by HiTech. I don't think I spent a grand total of $2000. $300 plus all the time I would spend tweaking and tweaking it adds up. Not sure if I would have the expertise then to equal what Lingenfelter and HiTech (Brian Ebert at the time) can do, actually, pretty sure I won't have their experience. They probably forgot more than I will ever know or need to know.

MavsAK

The look is the whole reason I'm even still considering Gen 1 SBC at all.
That the FIRST's intake flows as well as pretty much any manifold out there, serves 2 purposes there.... throw in the superior ecm, which is easier to tune, (or you can just plug and play and let it tune itself...), and the other goodies like having an LSX sized tb (and even needing it to maximise the intake....), is just gravy.

Over 300 cfm flow is insane for a non ported manifold.

If I were more concerned about it's all in performance, I'd just get a 6.2 out of a Denali, throw in a cam, remove the mechanical fan from it, get some long tubes and call it a day with 450 horses that'll still return upper 20s on mpg, and run smooth as glass.

Hell I'm still thinking about going that route. LSX just keeps getting cheaper and cheaper to do. If someone made a retro ltr runner setup for the LSX, no question what I'd do

aklim

I'm not into engine design so I can't say if flow numbers is the only consideration. I've heard short runners were trying to achieve something other than long runners and what not. IOW, is intake decision solely based on how much air you can flow and not port velocity or anything else? IDK.

MavsAK

Alot of the TPI's factory problems (and let's face it aftermarket problems too given how weeny sized the runners are, even AS&M runners.) come from the small diameter of the tubes. That's why they don't flow well.
The other half of the problem is the deplorably lower manifold design, with again tiny ports, horrendous angles, (and even the aftermarket units like the edelbrock//tpis suffer this too) That's again why they don't flow well.

The FAST TPI system out of the box will pull hard all the way to 5800 rpm, on just about anything smaller than a 406. I bet with full porting (and there's plenty of meat on the runners, plenum, and lower manifold yet for porting) it'd handle a 406 no problem.

Engine's just a giant airpump. The more air you can move through it at any time, the better. Sure it'll never be a 6400+ rpm engine... but it's mid range, torque will be far better, which will be noticed, especially in autox, tight road courses, and street driving. And let's face it, how often does the car really go into 6k+?
People have gotten into the 11s with a LTR setup using ported factory lower manifolds (which are terrible, even ported), and AS&M runners.
How fast do you need to really go? And if you're wanting to bust quicker than 11s...why aren't you going boost anyway, which really doesn't care nearly as much as intake flow characteristics?

The FAST will just get you to your goals quicker, retain a "factory" look, and comes in various option packages. Everything from just the manifold, plenum and runners, to the full ecm, sensors, wiring packages.
Same with alot of the plug and play kits really.
For me it's a question of where I'm driving the car. It's not going to see alot of 6k+ rpm. It's also a question of the aesthetic. The miniram and it's various cousins, aren't nearly as visually appealing as the LTR style. And if I'm ditching LTRs...I'm not even gonna mess around with a Gen 1 engine, because the whole reason of having one, is pretty much shot in the foot at that point, because the LSX does everything better.

Bandit1977

That's interesting, because that's pretty much the route I'm considering with my 88, install a First TPI manifold and a set of headers along with a decent exhaust system behind them.
I was wondering if it'd be worth doing on a stock motor, and how much (if any) performance improvement I'd get.
What were the problems with getting the fuel rails to fit?
Would like to know how much Don picked up with this mod.

BadSS

Here's some info that might prove helpful from an old May 1989 Car Craft article where they tested the FIRST on a basically stock L98.





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

The AS&M set up is an extrude honed ported stock base with their AS&M runners and ported plenum using a stock ECM, chip, and ignition 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 (HSR) and they brought a custom chip to use for testing.

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

Air Sensors, the FIRST, has a single mono blade throttle body (around 800 cfm) and at that time could only be bought with Air Sensor’s fueling only electronics that included a 4" MAF sensor. It deviated a bit on the ignition being a mechanical advanced distributor set at 6 degrees.

The test engine was basically a stock L98 with the old Edelbrock 1.5" / 1.625" headers running through an F-body dual cat exhaust system. I doubt very seriously any of the tunes on any of the systems were nuts on (the “ShortRam”/HSR probably was the closest) but I doubt they were way off either. While you might think the FIRST unit had an advantage of user tuning – I’m not so sure about that since the linear ignition curve on a mechanical distributor is better suited for a short runner intake. It did use a larger MAF sensor and throttle body than the rest but I doubt this internally stock engine actually needed it.

aklim

Every ramp I can hit, I WOT the thing if I think traction isn't an issue.

The manifold MIGHT be ok depending if profile fits what the builder recommends. Stock look doesn't do it for me. Any look doesn't matter. I'd go for a Hogan sheet metal intake if it makes the car run better regardless of what it looks like. Like I said, my hood is closed most of the time so whatever it looks like, I'm too busy working on it to see or care when the hood is open.

If you go with LSX, how much better will it be to justify rewiring all the stuff including the ECM and gauges? If all I gain is 10HP, it might be great for racing but not the greatest for cost vs gain for a street app.

MavsAK

Blasting down onramps isn't something you need a 6k+ motor for. Like I said before there's guys in the 11s out there on ported factory lower intakes, AS&M runners, ported plenums and upgraded throttlebodies.

That the FIRST is even better, is awesome. It'll also keep up with a stealth ram in peak hp and doesn't start running out of breath till 5800. It's torque curve is also a hell of alot better, which matters in road courses, and autox.

The engine I'm hunting for if I go that route starts with 403 hp.
A built gen 1 or 2 for that matter, is pretty stout at 450.
450 for an LSX, is just headers, tune, and a cam, depending on the motor chosen. Sure, I can build an SBC that will have that kind of power. But it won't have the drive ability, and it's not as strong as a block either, nor is it as light.

I show my car. I also take it and sling it between the cones, and drive alot on mountain roads. If I'm going to stop giving a damn about how the engine looks, then there's no reason to have a gen 1 under the hood.
Also, is easier to pass smog with an LSX. Not that, that is an issue in my state but it's still worth noting.

cv67

No need for a retro TPI for the LSx its there already. Runners have length, volume airspeed etc. If you know someone with a FAST manifold laying around pulll the lid off and ck out how they are designed

MavsAK

Yeah the runners have good solid length to them.
It's just a matter of the aesthetic. It's kind of like a hillborn type set of stacks. There's just something innately cool about seeing the long tube runners. Sure there's better manifolds, but there's a set of enthusiasts that love the stacks.
The LTRs are kind of the same way.

BadSS

There are many things to consider in engine design. However, the minimal cross-sectional area of the head sets the maximum RPM potential and the head flow determines the maximum HP potential for a given engine. Intake flow equal to or greater than the head flow helps to insure it will not limit the potential HP capability of the head. An intake with a minimal cross-sectional area equal to or greater than the head’s MCSA helps to insure it will not limit the RPM potential of the engine. HOWEVER, due to the physics involved, any intake runner length much over 3” on a SBC will start to reduce the RPM potential/capabilities. So, a longer runner (regardless of its MCSA) will never be able to match the RPM potential of a short runner intake on the same engine. Nevertheless, a large MCSA on a long runner intake like the FIRST (with the appropriate camshaft) will let you extend and make a lot more torque over the shift recovery point, or make a lot of power "under the curve".

When building a racing engine, as long as you’re not exceeding the part’s capabilities, RPM is king – it’s easier to make higher HP numbers at higher RPMs. For racing, big heads, big cam, steep gears, and high stall speeds are part of the “equation”. However, the “power under the curve” (a factor of shift point, stall speed, and shift recovery RPM) is a major consideration as well. You see a lot of tunnel rams on racing engines with runner lengths greater than 3”, so giving up some RPM potential for the extra power under the curve the longer runner length gives is not a bad thing even for a racing engine.

For a street engine, if you’re not concerned about the idle speed and vacuum and the stall speed and gear ratio, you can treat the build similar to that of a racing engine. However, most street engines are a compromise of idle speed, vacuum, stall speed, and gearing – the milder or the more compromised the build (smaller cams and lower stall speeds) the more critical that power under the curve becomes. Adding runner length increases midrange power but at some point it will take more power away from the top end than it can make up “under the curve”. That point will vary depending on different sized engines and with different transmissions.

For instance, if you’re running a close ratio manual transmission, the shift recovery rpm is higher than a wide ratio automatic, so you’ll have a narrower rpm band for the “power under the curve” (favoring upper RPM power). While making for a very spirited “driver”, it’s harder for a long runner intake like the FIRST to equal the quarter mile performance of a shorter runner intake like a single plane or HSR with a 5 or 6-speed transmission – especially with larger engines. However, it’s much easier for a long runner intake to equal and possibly perform better than a shorter runner intake with a wide ratio automatic and a “typical” 2500-2800 "low speed" stall converter.

Clear as mud,, right?

ch@0s

SO far its been tuned 3 times. The initial tune was just to get me started and was a mail order. Then I had it tuned once it was done. I changed the exhaust and it needed to be tuned again. Now I added headers and it needs to be tuned. Its running rich.

My engine was buit for nitrous. It will need to be tuned again once I get it on there and everytime I cahnge out jets its going to need a tune. I'm actually thinking of Getting HP tuners and learning to do it.
i

aklim

OK. I can see the mail order tune to get it going somewhere to get it dyno tuned. Not sure how much difference it made from exhaust that it needs tuning again. I wouldn't think it does change much from a cat back. I can see it with headers. Normally I do it in a batch. Save up money for intake, headers and cat back before I go get a dyno tune. After that, I would do heads and cam before I get the dyno tune. If I change a block displacement, I'd do it again.

How often do you change out jets? I'm asking because I haven't done much research into nitrous. I always thought you decide what you are going to run and go with that or how does it work? If I dump a blower, I wouldn't be changing boost every day but I can't be sure how nitrous works.

ch@0s

I have never had a nitrous car. For this reason I plan on working my way up to 125 shot from 75. Maybe I should just go with the 125 to begin with?

Maybe I didn't NEED a tune every time I made a change but It sure has "felt" better after every tune. Also, there is always that fear that without being able to datalogg I may be running too rich or too lean. This is why I'm leaning towards learning to tune and buying the equipment to datalog. At this point does a self tuning system make more sense? Maybe?

C409

.......... FYI ..... There is a chromed FIRST on thirdgen.org for $750 ask ...................

djzv70

I was wondering if you still owned it or did you sell the First Intake manifold? Also, what year of Corvette would it fit? And lastly, does it have facilities for emissions and EGR?

C409

..... I sold it years ago ! … Should fit any C4 … for details try … www.firstfuelinjection.com …..

djzv70

Would you let me know if you come across a First Intake Manifold?? I'm searching for one for my C-4. This manifold is still in production, but without the emissions hook ups.