Hi. I´m a Scandinavian (Norway) Corvette owner.. I´ve done some mods to my LT1 Corvette 1993 mod C4

* BB Tri Flo 3" exhaust (cat is gone)
* Melrose longtube headers
* Comp cam 07-503-8 / XR267HR-12 with Comp cam 26918 Valve springs
* Bosch design III injectors

* PCM for less tune

* Dynotune - AFR 12.4


Problem is that dynorun does not show expected increase in HP and torque (only 4-5 % increase both). Both curves (HP and torque) are slightly above old dynorun (before mods) through all rpm area. AFR is 12.4 and as far as I know that is OK value.

Apart from above changes engine is standard LT1. 48 mm standard throttle body and stock heads. I think the engine is not breathing well enough.

My question is:

* has anyone a good combination of aftermarket heads (ported heads) and 52 mm throttle body which makes the engine breath better and by that increase power..

Best regards,
Thomas

 

How much power did it put down? Also is it auto or stick? But to answer your question, you do need a bigger throttle body and higher flowing heads will help, as well as 1.6 roller rockers.

 

What trans ?
what gears?

 

Dyno results : about 305 HP (engine) and 460 NM torque (about 340 lb/ft).. I would expect close to 330/340 HP (engine). Increase from stock engine only about 12-15 HP..

The car has a standard (TH700R) automatic trans. Dont know about the diff, but probably standard ratio for 93 mod aut trans..

 

Not bad gains considering what youve done

Good heads and some work on the intake will wake it up plenty more

 

I think you need to do more to increase intake flow. there is a company selling a package said to make 330 h.p. with basicly all the things you have done. only things different in kit is 1:6 roller rockers,[your comp 503 cam is maybe even better], fresh air kit w/ k&n air filter and a air foil. hood clearence on the 93 is a issue so there are few fresh air kits avalible. I don't think you need a bigger Tb yet. If you did anything I would get a air foil. I don't think it would help a whole lot but wouldn't hurt.I don't like the metal ones as I worry that the bolt holding it on will come loose and go in motor.If you did go to bigger TB The cheapest way is to send your TB to one of those company's that will cut your stock Tb bigger and fit it with bigger blades & air foil. Maybe you need to work on the tune a bit. from what I've heard mail order tunes are not that great, It takes scaning and giving them info and teaking the tune a few times to really get big improvements. On my 93 I'm trying to copy what the kit does. Exotic muscle long tubes,1:6 proform rockers[not the greatest but I had them],comp cams 26918 spring kit,used obsolete AO engeering fresh air kit and K&n filter, plastic Tpis air foil clamped in stock intake coupler, Borla catback system. I looking for high flow cats and somebody to help work on the tune. I hope this is a enough difference to really notice. I wish had done a gear change first,but I'm working on that. Good luck Tim

 

If you've got the cash AFR 195 heads will help along with a dyno tune.

 

Porting an LT1 intake wont make any difference really with the stock heads they outflow them as it is. Now with a good head and cam its a real gain at that point.

 

Keep in mind the Four "C"s:

Cubic Inch Displacement
Cylinder Heads
Camshaft
Compression

Jake

 

Thanks for all replies. I think I will go the AFR way.
Regards,
Thomas