whats up everybody...

i talked to ken today on the phone and he will soon be making a big block version of the FIRST.... he also said that the runners on the big block runners will be abit larger at 2.00 compared to the stock 1.75 inch of the SBC FIRST intakes....

whats even better is he said that the "big block" FIRST runners will interchange with the SBC runners meaning we can now have a massive 2.00 inch runners on our cars... that means alot more flow and more power and best of all more rpms.....

of course you would have to open up the plenum becasue the stock plenum is 1.875 in diameter.. i will be one of the first people to use those "big block" runners on a SBC FIRST so....STAYED TUNED

 

Excellent news.

As it so happens I am in the process of mocking up a set of 2" ID runners just in case. Hmmmmm, maybe I need to change course. All one would need to do is take the head opening(Felpro 1205/1206) and match it at the base and taper it up to the 2" diameter where the base meets the runners. One could siamese the runners to adjust the length for wave tuning. Hmmmmmm.

 

yea big surprise..ken is always upgrading the FIRST..he didnt give a date but he said sometime next year. he told me that he has everything in works and should finalize the process in a week...i cannot wait to get my hands on those runners.. that will totally outshine any aftermarket GM tpi unless you port and weld like what you did 1989gtatransam..

i would love to have a 400whp tpi... i would hate to think what a 454 BBC FIRST would do : )... this opens up alot for people who have big blocks... looks like the tpi will have some pretty big power numbers... if you did some work on it 1989gtatransam im sure you can get well over 500whp with the FIRST...

 

I have an email off to Ken for the particulars. The wheels are already turning in my mind.

 

uh oh lol.... you always have a plan....lol.... i cant wait to see what the big block version look like

 

He's been working on these for while! Can't wait to see them, it will take a lot of SBC to max out a set of 2.00" runner!

What would be very nice is, a set of 2" with about 3-4 inch cut out, leaving a 14-15 inch runner.

 

This might just be the intake that gets me to stray away from my 2 Superrams. I would only make the swap if I can get the 2" runners though. I am pretty stoked to keep an eye on this.

 

ken is trying to make the FIRST the best performer for low, mid and mid to upper rpm ranges.... its going to be hard to beat a properly built up FIRST in those rpm ranges... edelbrock/accel/slp just cannot compare to this intake without MAJOR MAJOR surgery... the monoblade throttlebody that comes with the first flows 1076 cfm.. this is more than a miniram tb which is 1000cfm..

I consider this by far the best "street" manifold for the SBC because its makes a TON of power to where we do most of our "spirited" street driving and it pulls hard up to 5800 with the right heads and supporting mods for those who really want to have fun on the street..

i mean when i switched intakes i could not believe how much more mid range torque i had gain from this.... it definitely feels good....the best way i can explain is like with the FIRST the power kept growing as i went higher into the rpms kinda like a turbo car.... while the edelbrock/tpi just had a quick burst of power and it was over...

 

Saw this quote on another web site while doing some research. This is talking about long tube runner intake systems such as TPI.

"The runner length is always the dominant spec in determining the shape of the TQ curve. Larger diameters allow that shape to not choke off the motor earlier. That's the jist of it. Your peaks should still be in the same place but it should hang on to the power longer"

Exactly my thoughts. Make the diameter of the runner large enough and you don't lose a thing as long as you still maintain the correct air speed. You can get the best of both worlds. That is why I am glad to see First stepping up to the plate.

 

a manufacture has finally figured it out..i will definetely be porting matching my plenum to those new runners i think the base is already wide close enough to 2.00 diameter... i want these runners now lol.....

 

88fastgta. The runners a certainly part of the puzzle and a big piece of it. However the intake manifold/base is another part. I have not seen the latest style but I would suggest maybe that it might need some work for best performance.

I would suggest taking the cross sectional area of the AFR intake port opening and carrying that CSA on through the base runner and towards the end open it up to match the new 2 inch Id runners. I would make the opening to the AFR head maybe .020" less on each side to allow for some wiggle room alignment wise. Then open it up say a 1/2 inch past the opening. On the opening at the base to the head I would leave the bottom edge alone and the center edge alone. Just open the outside edge and the top side.

 

Glad to see that Ken is looking to keep improving an already great product. These larger 2" runners would work the best on large engines (454+). Yes they would help engines smaller than this hit a higher rpm for peak torque but I'm concerned you would loose the tuned effect of a TPI intake.

There are other combos but here is an example. A stock FIRST unit is really matched for a 383 with a 268 intake duration cam. This will produce tune rpm range around 4,400 rpm. Increasing runner diameter to 2" moves peak torque up to 5,750 rpm however the tuned rpm value is still around 4,400 rpm. This is a mismatch of 1,350 rpm. You would have to shorten up the runner length from 8.75" to 3.5" to get the tuned rpm more in line with peak torque. If you did all of this, you would still have to have a good rotating assembly, converter and drivetrain to handle more power at a higher rpm.

 

blackdog 36.... my engine consist of a 4 bolt main forged 355 vortec block, box stock first, gm hotcam (218/228 .525.525 lift), and unported l98 heads... where should my peak hp and tq be at.... im planning on upgrading to 180 heads...

 

88fastgta,

Your tuned rpm for 3rd harmonic is 4,300 rpm with a 279 advertised intake duration (for LT4 hotcam) on stock FIRST. Your peak torque rpm is 4,850 rpm for a 350 engine. Is a little bit of a mismatched. I am not sure how important "exactly" matching up these values are. I do believe that knowing your tune rpm is important so you can build everything else around it. Even with the calculated mismatch, you note how good your engine now runs.

I've attached graph showing tuned rpm based upon your cam vs different engine sizes at varying intake diameters. The tuned rpm based upon your cam and intake length is the horizontal flat pink line. The diagonal lines are different engine sized showing peak torque from varying intake diameters. The graph shows that a 383 or 400 engine would be better suited for your cam with stock FIRST.

I think you are still fine with stock first on 350. The larger 2" runners would be overkill for you. Better heads like the 180's or 195's would help a lot. Keep us updated. I appreciate all the info you have been posting here, especially on the FIRST install.

I read somewhere that optimizing your intake path based upon tune effect will be comparable to a 1 psi boost. Tuning your exhaust could free up more power by generating 3-4 psi of sucking pressure. I'm going to try and build an exhaust that is tuned to the same rpm as my intake. 1989gta has done a lot of work towards this with his headers and exhaust termination boxes.

 

hmmmmm... well i guess i will stick with the runners that came stock on the first.... i know it would take alot to really take advantage of those bigger runners... the car runs good with everything on the car.... its getting tuned as we speak so hopefully it should be a little better... i know i can do alot better because i already know the heads that i have now are a big mismatch for the hotcam and first..also running heavy *** stock vette converter makes it worse....i will step up to a vigilante 2800 stall.. i had ran out of funds so the heads is the last big piece on my engine that will be changed...

 

yeah i see your point... if i went with the bigger runners i would be over 6000 rpms with that... i dont want to spin that high even tho i have the shortblock to handle it.... with all the fun street driving i do i like to keeps the revs under 5500 rpms to where i actually use all my power.....

 

That seems high for a 350 with a hotcam. I'd expect closer to 4000 rpm to be honest, maybe even alittle less. I've seen some dynos as low as 3500 rpm peak torque, depending on intake and heads. On a TPI it will be forced in the 3000-3200-ish range due to long runners. LT1's and LT4's seem to make peak around 3800-4000 and hold that to 4400-4500 with the hotcam

Heres a nice thread of TPI dyno with hotcam on stock L98 heads/stock runners/siamesed stock base/stock plenum. 275rwhp which aint bad. Peaked near 5000 rpm but held to 5500. Thats the cam doing that. Intake cant support more rpm and the wider duration split keeps power hanging on
https://www.thirdgen.org/forums/tpi/...t4-hotcam.html

With with FIRST TPI, i'd bet thats near 300whp easily



And IMHO, a big block using the FIRST would want alittle more than 2" runners or else you will have a very low rpm motor. A big SBC moves ALOT of air. A bigger BBC moves even more air! They use 260-290 cc heads on mild combos! They have 1.56x2.24" intake ports, which is bigger than sbc 1207 gaskets! They breathe

 

I determined peak torque form two online calculators. Trying to find actual equation. It might just be a general rule of thumb formula though. Also maybe these formulas are for ideal situations and what actually happens in a fully functional car is a little different.

 

that gives me a good base of where i am at... i should at least have 275whp.. my engine is freshly built and i have abit more mods than him... it would be cool to take this to the dyno and see 300+whp with l98 heads... if so that mean l98 unported heads are good to about 300whp which i know alot of guys want to see me dyno.... hmmmm 50 bux i can go to downtown raleigh and get a dyno sheet and see where im at.... im very curious to see as well what im putting down..

 

Good move,, with your combo, you probably would loose 20-25 lb/ft TQ with a 2" runner and not pick up much of anything on the top end of your current combination.

Yes,, as other have pointed out, you need a very agressive combination with more than 355 cubes to take advantage of the 2" diameter,,, unless you're planning to siamese the runners to make sure you can pick up on the top what you'll loose in the midtange.

There will be a few combinations out there that could utilize the 2" runners - like a 441 FIRST,, but I'd rather see Ken take out the creases in the existing runners,, making them look like an SLP runner,,, so "we" could easily siamese the things. That would help out a lot more combinations than the larger diameter,,, considering 95% of the SBC combinations that would use the FIRST would benefit more from effectively reducing the runner length.

 

88fastgta. I don't know why but I thought yours was the combination that had the XFI280 camshaft. The 218 camshaft will not allow you to rev high enough to take advantage. With the 228/228 camshaft my 355 motor was making peak power around the 6400 to 6500 rpm range. Peak torque was around the 5000rpm mark.

 

nope.. just a little old hotcam... i didnt want to get too crazy with a huge cam on stock heads... i wanted to keep the meat of the power below 6 grand... the reason i went with the hotcam is because its a popular cam for highflowing tpi's and at the time it was cheap compared to all the other cams and it sounded more aggressive compared to the xfi 268 cam ( i know you shouldnt choose a cam by sound but i was younger then)...

also people like kevin91z and some others had great proven results with that cam, something like 320whp with vette l98 heads and ported out aftermarket tpi and the usual bolt ons and tune... if can get 355whp with 180-195cc heads then the hotcam is staying in... my goals would have been achieved for this car..

my car rocks with the hotcam... MUCH stronger than the stock cam and the old powermax 2032 cam i had... hotcam is designed for lt1 motors but it works really really well in my application..

 

You are doing fine with your build. I just got your car mixed up with the one that has the AFR 195 heads and the XFI280 camshaft.

 

oh lol... i think thats gbayfisher... he has a FIRST, 383 engine, afr 195 head and a cam like that... im sure he could benefit from those runners...

 

"i think thats gbayfisher..."

You are right. That is the car I was think of.