I'm from the corvetteforum, but I've been directed here to get some input from you guys, as I'm told, and have seen this is a really knowledgable TPI base. Yes, it's a corvette, but the question is about the engine/cam selection and not the car.

I posted in here a couple weeks back about a 383 build I was considering building, but now my decision is refined down to just the cam. I know not everyone would agree with my decision to stay with the stock TPI instake, but I've decided to do it based on a couple of factors.

1. Torque beats HP on a daily driver
2. Cost savings

Hopefully this is the last help post I'll need about this engine/build. I decided on a vendor, an engine build, and on sticking with the TPI intake to favor torque over HP.

Poll: Which would be a more fun C4 daily driver 350HP/450TRQ or 400HP/400TRQ? - Corvette Forum

This car will be a daily driver and will see the track maybe once or twice a year for fun, but not competition......so a high RPM screamer isn't as important as fun daily driving.

My car is a 1990 Corvette L98 coupe with a manual ZF six speed transmission.


Mods:

• 4.10 gears,
• Hedman Elite Headers,
• True Dual 2.25 inch Exhaust with Borla XR-1 mufflers
• Steel Single Mass Flywheel, and Spec Stage 2 clutch.

I'm having a 383 Engine built with the specs below. I sent the vendor (Precision Factory Rebuilt Engines - Houston - Remanufactured Engines) my 113 heads and lower intake which he is porting and match gasketing and assembling to the 383 shortblock.
Specs are below.

 GM 5.7 block bored, honed, decked and align honed
 Durabond cam bearings
 Matching roller lifters and springs
 New sir steel rods 5.7”
 New cast steel 3.75” stroke
 Crankshaft micro-polished less than a 12 ra finish- (Eagle or Adept)
 Speedpro pistons with Molly rings
o 10 to 1 compression ratio
 Balanced rotating assembly
 New Melling timing set
 New high volume oil pump
 New gasket set
 New push rods
 New head bolts
 Customer’s aluminum cylinder heads will include the 2.02/1.60 valves
 120 lbs. springs
 3 angle seats
 Bronze guides
 Positive seals
 1.6 roller tip rockers
 Ported intake and exhaust runners
 Internally Balanced

I just need to figure out what cam to go with. The vendor suggested these two models....The first cam, up front, but then the second cam after I directed him to some threads I have here on the corvetteforum, and here at thirdgen forum. He felt the second cam might better match the TPI intake airflow restrictions after reading the threads

First cam
o 224/232 @ .050
o .501 lift
o 112 lobe center

Second cam
o 210/215 @ .050
o .470 lift
o 110 lobe center

I called CompCams and asked for their recommendation - Compcams said the 08-501-8 would be a good match for a TPI 383 setup. He said this cam would make good power on a 350 between 1200-5200RPM, but on a 383 stroker between 1000-5000RPM.
o 212/218 @ .050
o .488/495 lift
o 112 lobe center
Camshaft Specifications

I would like one final sound off of help from this board in helping make this engine as strong, fun, and reliable as it can be for my daily driver application with the ported TPI intake. I should note that the car will be running on 91 or 92 octane gas because that is the highest available in my area.

One last request---If you don't know what you are talking about please don't post(just read and learn with me), because it's hard to distinguish on the internet, who is speaking from exp, and who is rattling off unknowns.

 

I have the 113 L98 heads too, and I cant see how you can get 2.02/1.60 valve in them. Its been a while, but the largest I have seen on those heads is 2.00/1.56". Second, if you havent put the engine together yet, if you're using the stock TPI intake, do a search for "siamesed intake" and follow those guidelines. All it takes is a 1/2" to 1" of porting, and the intake will flow a lot more air and make a lot more power.
The second and third cams are small for a 383, but if you dont siamese the intake, go with the Comp suggestion. That will get you the 350/450 goal, as my previous combo with a 350 and ZZ4 cam put 319hp/419tq to the wheels with a stock ported (not siamesed) intake.
If you do siamese the intake, definitely go with the first cam suggestion. Its worth at least 25 HP and TQ more. Also keep in mind you will need to have a custom chip burned to handle the larger cubes and larger camshaft.

 

Go with the first cam. Comp's recommendation is a little better for the power band of the TPI but if you have it down to those 2 choices I'de go for the first cam you have chosen, it has a better LSA for fuel injection, more lift, and more duration, all of which will work well with your 383. Have you ever considered doing a ZZ4 cam? Or an LT4 hot cam? The hot cam would probably be better suited to your engine, is OEM equipment, and can be had on average 100 dollars cheaper than an aftermarket cam.

 

I used to have a 383 with a bone stock TPI on top, it was a flat tappet motor and I ran a comp 12-256-4. Spec's 212/218 @50 .449/.456(w1.5's)lift 112LSA but I ran 1.6rr's.

It dyno'd 271.3rwhp and 400.1rwtq.

 

Well thats pretty solid information right there. Hard to put a real number on drivetrain loss but thats somewhere between 300-350hp and 450-500tq at the crank depending on what magical factor you feel like using.

I'd still go with the other cam I suggested (218/224), but then thats me making my own decision I had a 212/212 .444/.444 112LSA comp cam in my 305 for a while and it was pretty mild. I wish I had gone with the 218/224 instead. With a 212/218 in a 383, at least nobody will ever know it has a cam... not necessarily a bad thing. Should idle pretty much like a factory stock vehicle.

 

I'm going with a 383, AFR 180 cc heads and bigmouth/SLP combo, ported plenum. The 08-503-8 from comp was recommended to me. Anything you do with a 383/TPI is going to make a ton of torque, you may want to consider going with shorter gears in the rear. I currently have 3.70 and I'm probably going back to a 3.23 for this reason.

I expect to pull pretty good to about 5500 RPM, I know my TPI combo will be done a few hundred RPM before this but remember, in the shootout the TPIs stopped gaining around 4800-5000 but they didn't drop off at all until well past 5500. You'll still accelerate plenty, just not as fast as you do when it hits stride in the 4000 range.

 

i have 373 and i can say if your using it on the street, ditch the 410s and go with some 323 at most 342s. the 373s are just a little too much for the tpi, i myself will be going back to 342s later.

 

I think you are splitting hairs somewhat. These cams are different but only marginally so. The LSA might have more of an impact...??

I would go to Performance Trends and download their desktop dyno and run it with the different cam profiles to get an idea of the characteristics and differences. These programs are good for showing differneces, not necessarily accurate as far as predicting true performance. However, the more time you spend setting up your exact engine the better it will be.

Engine Cycle Analysis Dynamometer Performance Simulation Software Program

I would also get the cam technical specs... valve open and close degrees. Also, some mfg's will set their specs using different rocker ratios so this makes it hard to compare apples to apples.

 

I gotta recommend the old stand by: LPE219. Passed emissions, idled at 750 rpm, ran good in the bottom end and midrange and with the superram on a 383, never had a problem spinning the tires. You will need more spring though, and I would run them with 1.6 rockers.

 

I RAN A 383 TPI WITH TPIS MINIRAM AND A ZZX CAM ALSO TPIS...GREAT SETUP..IF AN AUTO USE A GOOD 35 TO 3800 STAHL CONVERTER..NO TCI ETC SPEND THE MONEY ON THE CONVERETER IT MAKES A DIFFERENCE...

 

yup, sounded bone stock was quite the little sleeper.

Easy to tune too