I am relatively new to this as you can see I only have about 50 posts or so.... I have always worked on my own cars but, this was my first build... with a couple of friends help pulled my motor built a new motor (sold the old motor) I assembled it my my garage and dropped it in. I had lots of hitches lots of curve ***** but all in all it all got done. When I dyno'd the car I was really disappointed with the numbers. My question is what really effects these numbers. I didn't have full bolt on's done. I am running the stock drive shaft. when dyno'd I didn't have the right plugs. I am running the stock gear and a 2500 stall. (which is what was recommended by comp for my cam). I had a flowmaster which is now a magnaflow I have since picked up but not installed yet my plugs NGK FR5, a under drive / over drive pulley set, a msd coil and msd 6al box and a 160 deg thermostat (I was running hot). What will these mods really give me come dyno time? The tune is garbage so I had to find a new tuner (I wont go back to the other guy he is a ). Does a gear affect rwhp or torque? Does that info just get typed in a figured in to the computer and if that is the case if he didn't enter the right info in the first place the dyno numbers would be wrong to begin with right? Sorry I know I am all over the place. let me know what you think.


At time of dyno

96 383 stroker motor
4 bolt splayed
Lunati crank
Oliver I beam rods
je inverted dish pistons (low compression about 9 to 1)
comp cam 290 hr-12
comp cam promag roller rockers 1.6
AFR 210 heads
2500 stall
BBK 58mm throttle body
lt4 intake port matched
pacesetter long tube headers
off road Y-pipe
flow masters
moroso cai
lt4 knock module
all clevite bearings

 

What are the numbers? That cam is mild for a stroker. What injectors are you running? Im sure the low CR is not helping at all. Your stall shouldnt be hurting you, but its not helping. You should be running between 3600-4000.

 

315/319
sorry I knew I was for getting something 36# injectors

 

??? was this on a dynojet? Im making more than that at 5K and most cam only setups are making more. Id say your tuner had something to do with it. If you were running stock manifolds i could see that. A gear might cost you a few, nothing noticeable

 

see and that is what I thought I expected to be close to 400 at the wheel and that was because of the pistons.... I know the 6al and coil pulleys will help but it's not going to give me 80rwhp. I am disgusted with this the car runs like **** it bogs it backfires and I just feel it has something to do with the tune!

yes a dynojet

 

Check the opti?

 

if it is the opti wouldn't it show a code?

 

That's about what I would expect from a car with your listed mods.

There are so many things working against you it's insane.

 

care to elaborate?

 

The compression is the big thing. You're a full point and a half down from STOCK, much less a performance-oriented build. On a build of that potential (which I would target at LEAST a 12:1 c/r), you're likely losing close to 40HP, maybe more, from the compression alone.

The 306 is older technology and many people swear by it, but the wide lobe separation isn't doing you any favors in terms of peak HP. A custom grind from AI and matching portwork on those heads would easily put you over 400HP. ****, my ported stock castings and a cam comparable to the 306 gave me the dyno numbers below.

Your stall is also incredibly low. For max performance you should be targeting something around 3600+. A 4000 stall would be ideal, IMO, depending on a more tailor-made custom grind cam.

Your exhaust is also a negative, particularly the Blowmasters. They're costing you HP, undoubtedly. Ditch them for something more freer-flowing - even just adding a cutout will help to free up tons of HP.

 

You have a stout foundation, my next step would be a Procharger.

 

96 383 stroker motor
4 bolt splayed
Lunati crank
Oliver I beam rods
je inverted dish pistons (low compression about 9 to 1) Id say this is the main issue
comp cam 290 hr-12 This isn't helping either, very mild for a 383
comp cam promag roller rockers 1.6
AFR 210 heads ported or out of the box?
2500 stall Rip that out immediately
BBK 58mm throttle body
lt4 intake port matched
pacesetter long tube headers
off road Y-pipe horrible merge
flow masters you fixed that already
moroso cai
lt4 knock module
all clevite bearings

 

why 9.1 compression??? there is quite a bit to gain just there I would assume.


edit.
wow within seconds of me posting this i had 3 people say the same thing 0_0

 

Because 99% of engine builders are blind to the capability of the LT1 and it's ability to handle high compression ratios.

 

It came stock with a good compression ratio

I don't know why any engine builder unless for boost would go under stock compression

 

10.5:1, stock.

 

Thats what im saying it came stock with better compression then the build listed

 

I found this motor set up the person who originally put everything together was a mechanist and had intentions of forced induction. He owed money to the shop owner and I came walking in the door and told him I was going to build a 383 brought him a block and he said I have exactly what your looking for. If and when I can afford to do a procharger I will but I still expected more... now the cam was not part of that deal I already had it from something else I had started and changed direction on. flow masters are gone and the torque converter was what comp cam recommended I didn't research it to know it would of been better to go higher I went with what the specs called for.

What does a custom grind from ai run?
the heads are out of the box I thought that they would be fine seeing how they are already opened up compared to ported stock castings. Or so I thought!

 

10.4

The compression is hurting some, but not enough to dyno that low. Something else is going on.

If its backfiring and **** obviously you need to get that addressed before you go any further.

 

Sounds like another mismatched combo. Heads arent flowing great, you have a cam meant for a 350/355, compression is wrong, stall is crap