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C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

Torque Build 350 Centered Around FIRST TPI

 
Old 05-06-2019, 12:14 PM
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jonbonez
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Default Torque Build 350 Centered Around FIRST TPI

So as the title suggests, building just a little bit of a torquey build around the FIRST Intake. You can check out their website here and see what they've got, great looking products and Ken is a real nice guy to talk to and he knows his stuff.
Link: https://firstfuelinjection.com/products
Currently the engine is a completely stock L98 with upgraded injectors that are close to stock but are better than the old ones that gummed up from the new fuel mixtures in today's fuel. The vehicle is an '85. I plan on pairing the intake with a 195 cc style cast iron (I chose this because the original block is cast iron and I'd rather not deal with the problem of having two different metals that will heat up differently and react differently) head with a 2in intake valve seat and 1.5 rr arms. The intake and heads will be paired with a flat tappet camshaft with 110 - 114 LSA and a base line duration of 220. I've looked into roller camshaft swaps, but I'd rather use the block until I can't anymore, then I'll buy an aluminum block with the roller cam capabilities. The engine will also stay as a 350. Much later down the line, I might install a turbo kit or procharger kit. The '85 years came with that one year only forged internals which is lucky for me, so that means I'll be taking all the boost. I can imagine that with this new setup the powerband will probably go just a bit higher because of the decently larger throttle body and intake runners etc. So it'd be wise to bring the stall from about 1500 to 1800 or 2000, not too sure on that one. My knowledge lies more reliably in the engine bay then inside of a trans tunnel, so I'd need to learn more.

For the brain of this, I'll use the Tec GT electronics that are paired with the FIRST intake on their website, that'll allow tuning to be a million times easier than, swapping to a new ECM and repinning my MAF all to just have to deal with swapping chips in and out. Wiring this should be a piece of cake and keeping the original gauge cluster should be easy as the only thing I'll have to wire to it from the new ecm would be the tachometer reading. Now I know I'm not the smartest or wisest when it comes to engine tuning or building, but I think this is a neat little build that will keep up with some of the newer "Furd" Mustang kids on the road, hopefully enough horse to do just enough to compete in a roll. This car won't be a drag strip queen though, I plan to use her as just my classic car that I like to drive on the side. Later down the road I'll save my drag strip plans for a C6 Z06 once I can get my hands on one cause gotta love a 427.

A side question, if I were to go ahead and get the 195 cc cast iron heads and cam shaft that are for this build, would I lose any power and what kind of shift in the power band would occur putting them under the stock TPI? I understand the cam and heads would be choked but it's not like they'll be that way forever, the stock TPI would just be there as a place holder. Could I go without having a tune possibly? It'd most likely be cheaper to go ahead and acquire the build's heads and cam to save money instead of get an "in-between" set. I am about to have to change cylinder heads regardless due to a valve cover bolt puncturing the water jacket. It is sealed currently with thread sealer. The motor as it stands, leaks out the front seal, valve cover, oil pan (maybe), rear main (probably, torque converter cover has engine oil in it), and possibly the oil sender. It may look like much, but the oil loss is rather minimal, I only have to dump a bottle of oil in every 1000 miles or so. If I were to do the head swap, I'd probably just go ahead and get the heads/cam swapped and then fix the front main, oil pan, and oil sender. Probably will leave the rear main for another time such as when installing the new Torque Converter.
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Old 05-06-2019, 02:47 PM
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Kevova
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Quite a tale. If you're going to redo the top; might as well do the bottom. Stock TPI runs out about 4500-5000.

Last edited by Kevova; 05-06-2019 at 02:48 PM.
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Old 05-06-2019, 10:50 PM
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Originally Posted by Kevova View Post
Quite a tale. If you're going to redo the top; might as well do the bottom. Stock TPI runs out about 4500-5000.
By bottom, do you mean the block? It's an idea but definitely not off the table in the future.
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Old 05-07-2019, 07:52 AM
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Yes the bottom would be the short block. Increasing stroke would also increase stroke.
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Old 05-07-2019, 02:19 PM
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Interesting to see that intake. I wish the website had more information about them, like runner size, plenum volume, etc.
Theres a Superram on Ebay for about twice that price, and lots of information about them. I'd love to have the superram, but not for what its selling for.
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Old 05-07-2019, 02:28 PM
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Originally Posted by 64Scout View Post
Interesting to see that intake. I wish the website had more information about them, like runner size, plenum volume, etc.
Theres a Superram on Ebay for about twice that price, and lots of information about them. I'd love to have the superram, but not for what its selling for.
I have seen dyno graphs posted on another forum of guys using the FIRST. It pulls well to 5000 and holds pretty well to about 5500 before getting choked off, but peak power is around 5K.

Jbaonz, use aluminum heads. It is a very common set up and you pay a weight and power penalty for fearing the aluminum. It's about as bad as thinking carbs make more power because you can work on them and having a 3/4 race cam. This is old school folklore. Hell, they put aluminum heads on iron blocks in the 60s, if not before.

Your fuel injectors didn't clog due to new gas. Gas is cleaner today than before, the seals break down due to ethanol.

Your cam is not a good cam for a blower set up. I would suggest calling Lloyed Elliot and getting a custom cam for a custom build. If you know you are going to run a blower, I think a 218/228 on a 114LSA will be good, but I would call him before making a pruchase. Otherwise with that intake, you will probably want to run a 220/224 on 110 or 112 LSA if staying N/A.

How many miles are on your bottom end?>

Last edited by KyleF; 05-07-2019 at 02:30 PM.
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Old 05-07-2019, 09:32 PM
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Originally Posted by KyleF View Post
Your cam is not a good cam for a blower set up. I would suggest calling Lloyed Elliot and getting a custom cam for a custom build. If you know you are going to run a blower, I think a 218/228 on a 114LSA will be good, but I would call him before making a pruchase. Otherwise with that intake, you will probably want to run a 220/224 on 110 or 112 LSA if staying N/A.

How many miles are on your bottom end?>
The whole short block as a whole currently has 140,000 miles on it, but the engine is in pretty good condition. Vehicle was maintained well and kept in storage through her whole life. Plan is to stay naturally aspirated primarily, so I'll be going with the Comp Cams CL12-210-2, but you also can't beat a custom build. And yeah on what you said about the injectors, yeah that's about right, that's why there's currently brand new injectors in it.
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Old 05-07-2019, 11:19 PM
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The hotcam will have more lift than the old 268...are you stuck on a flat tappet cam? If so consider the Isky 264 or even the 270 mega cam.
Custom cams for this are a waste of money, chances are its going to be an off shelf deal anyways. Many custom cams are,

Id do the first, guys are asking bend me over prices for SR, old tpi bases. The first is new, flows well and looks cool. PLus easier to take apart.
The SR is good, better with porting but its too much and still rpm limited.

140k its time. Pull it out do it right youll be glad you did believe me!!!

Last edited by cuisinartvette; 05-08-2019 at 02:49 AM.
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Old 05-08-2019, 01:01 AM
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Isky 264 seems like a great choice but it's got that 108 LSA and 2000 beginning operating range, I'd like to keep the operating range at least closer to 1500 since that's right where a TPI even the FIRST will start it's torque, and it won't be a drag race car, it will be running at 1500 - 1600 RPM 90% of the time down country and city roads.
And yeah, I'm sticking to the Flat Tappet cam set up right now, I know I start out at a disadvantage without the more agressive capabilities of a roller tappet set up.
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Old 05-08-2019, 02:50 AM
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Ive run that 274 in a NA 350 and SC 383...its a fantastic all around tq cam. Even with strock converter and 3.08gears. Not smooth nor lumpy but you know "its got a cam".
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Old 05-08-2019, 09:28 AM
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Originally Posted by cuisinartvette View Post
Custom cams for this are a waste of money,
Funny, Lloyd's price on a custom grind for my LT4 shipped was quoted at $10 higher than an "off the shelf" from Hawks not including shipping. $15 less than a CC305 from Comp, again not including shipping.

In my case, it would be cheaper to go custom from Lloyd.

It never hurts to make the call and get a quote. I feel pretty confident that Lloyd has more experience than most if not all of us forum members. Whenever you buy parts, you should look at different options to see if you can save a few bucks anyway

Last edited by KyleF; 05-08-2019 at 09:30 AM.
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Old 05-09-2019, 12:51 PM
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I'm on the side of those who recommend doing it right over doing it piecemeal on a 140K mile L98. All that intake will not make much of a difference if the cam, heads, and exhaust can't move the air. This would be the time to pull the engine. If I were you (and I'm thinking about doing exactly this to my C4 L98), I'd build it as a stroker 383 or even a 400/406, put different heads on the engine, put a decent, street-friendly cam without too much lift, put some headers on it, get the FIRST intake and heads ported/matched, and then put it back together... and you'd get close to or over 400 HP at the rear wheels. That would likely run you around $10K to $12K, but you'd double the RWHP and have a car that would outrun a base C7 and give a Z06 a good run for the money.

By stroking the engine, you can gain low end torque without using small-diameter long runners to get velocity at low RPMs. The increased breathing of the FIRST should put you into SuperRam territory, and given the engine I've described would not really have a torque falloff until well above 5K RPM. Really, this is what Chevrolet has done with the LS engines (better breathing creates enough torque at low RPMs so that the intake doesn't have to sacrifice HP at higher RPMs... that's why they're 6.2L instead of 5.7L). Just bolting on a FIRST TPI without the heads, cam, and exhaust to handle all that air might gain 30 HP, and actually lose you low-end torque.

Last edited by obijohnkenobe; 05-09-2019 at 12:56 PM.
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Old 05-09-2019, 03:15 PM
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3 out of 4 "custom" cams Ive ordered turned out to be shelf grinds...the "custom" bit is someone picking one for you with their name on it thats all, dont be fooled. Sure Lloyd does plenty of custom grinds my comment is not meant towards him...its most tuners. They are fulll ot it. My Isky done to my specs was $350, billet. Doesnt have to cost a lot .Ironically its very close to an age old grind they have; had I known that Id have saved a few bux
The 350 has had a million grinds made for it, unless someone wants someothing 1-2 deg different to say they got a custom cam go for it.


Where is the OP
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Old 05-09-2019, 05:02 PM
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Hey obijohnkenobe, great ideas there for sure. I just left out the part of the exhaust, I am getting some TPIs Headers and those will flow nicely, pondering on deciding between hi flow cat or delete the cat and figure out the AIR removal. I also do have a heads and cam that in mind that I will use. Looked into the Isky's that cuisinartvette suggested and they're a good bachelor. For the heads I'll just get some 180cc AFRs. As for the motor I'll rebuild it at a later point in time especially when I have that 10 to 12k available. Looking for really only at least 350 RWHP. Thanks for the info though on the displacement differences, didn't know I could stroke a 350 block to 400 or let alone 406.
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Old 05-09-2019, 05:06 PM
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You cant. 400 crank with turned down mains makes a 383. (3/75 crank)3.875 makes a 396
Some have done a 4: crank but wouldnt recommend it plus you need the heads/intake to suport it
A 180 head, 2tee-20 cam intake porting used aftermarket runners, headers, tune thats all you need.
Should be a solid 13 sec car if not better that will drive anywhere. A good street car leaves a light and hits 60 quick a built tpi is good for that
All the rest is track/yt stuff ( I own one) not so great for normal use. Hp numbers are neat til you gotta live with it, requires a high tolerance and $.

If only I could practice/preach lol.

Last edited by cuisinartvette; 05-09-2019 at 05:07 PM.
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Old 05-09-2019, 07:59 PM
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A SBC bored out to 4.125" x 3.75" stroke will give you a 400 ci engine. I think you can go as far as 4.25" bore on a SBC and that gives you a 427 ci engine, which is what I believe Chevy did with the 2013 GS 427 on an LS block... they might have had a little less bore and a little more stroke. But, honestly, a naturally-aspirated 400 ci engine with today's head, intake, and cam technology is going to be a very strong street engine and you have at least one rebore/rebuild in a cast iron block. In short, when it comes to usable horsepower at reasonable/street RPMs, displacement has a quality all of it's own.

I'm going to build an engine for my C4... it will likely be based on a World Products block set up as a 400 ci engine. If FIRST creates an intake manifold that will allow me to bolt it up to LS heads, then I'd go with the FIRST TPI to fool the unobservant on the Motown LS block... otherwise it might be one of their 4-bolt main short blocks with billet steel caps. I think that over 400 RWHP is reasonable with excellent idle and driveability… and it would be very competitive with a factory C7. In the meantime, my L98 has long tube headers and a full Corsa exhaust, the easy bolt-on intake improvements, AIR pump and EGR removal, 1.6RR roller rockers, a mild but more robust than factory cam, and a tune... and this has likely added about 40 RWHP to the engine putting it at around 250 at the rear wheels (I am going to get it dyno'd in the next week or two to get a baseline). I think that level of performance is pretty easy to get with bolt-ons to a non-worn L98 (mine has 52K on a '91).

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Old 05-10-2019, 11:06 AM
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I'd start with this https://www.summitracing.com/parts/mll-bp3834/ add accessories of your choice, heads and intake, and keep driving the car as you put the new motor together.
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Old 05-10-2019, 05:23 PM
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2k that is cheap..BP makes their own 400 block also dont know much about them
Obi points out a very mild 400 is a good choice That extra bore makes a noticable difference even though it doesnt sound like much.
A nice 195-210 head, reasonable cam, converted LTx intake would haul azz and keep a nice idle. They make enough torque without having to use a long runer intake to get it.
Regret not doing one, just didnt trust a GM block to 7k+ beatings.

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Old 05-11-2019, 11:05 AM
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Originally Posted by cuisinartvette View Post
2k that is cheap..
I kinda wonder how that would work with a cam and stock heads and intake. I just sat here online and priced out some other parts and came up with $6500. I dont have desktop dyno to plug all that info into.
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Old 05-13-2019, 01:32 AM
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Here's the problem with a ton of low-RPM torque... how are you going to get it to the ground? The newer Corvettes have traction control that will effectively weaken the engine to the point where the tires won't spin, so you get the maximum torque that can be effectively transmitted. We don't have these systems on the C4. All we have is an educated foot, and even so you're only going to be able to transmit so much power before the wheels start to spin... more than that is wasted in the form of smoke and heat and noise. If you put a 1,000 HP motor in a C4, then you need to be an expert to have a chance of staying with a C7 Z06 or better... the C7's computer is better than most of us.

The more I think about it, the more a 420-450 HP motor makes sense in a C4. That's going to get you a 3.7-3.9 sec 0-60 and a sub-12 second quarter mile, and I don't think you'd be able to get much faster than 3.7 seconds with a C4 with street tires regardless of the motor... you can't hook it up with extra power. It might be that the FIRST TPI would be overkill and a tire-spinner at lower speeds, while also restricting HP at higher speeds, and something like an LT-1 style intake or MiniRam would be the way to go. I think the advantage of a 400 ci SBC is that you could run a mild cam with a nice idle (that sounds like the factory L98) while having enough torque and HP on hand to keep up with anyone until well past 60 mph... the ultimate sleeper.

What would be interesting is to send a FIRST TPI to a company like Blueprint that dyno's it's long blocks, and have them dyno the thing on a 350, 383, and 400 ci small block. That would provide enough information to see what the limitations of that intake are on a built engine... if it is a worthy substitute for the no-longer-available Accel/Lingenfelter SuperRam, if it's more, or if it's less.
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