Recently got done with my 355 rebuild looking to make more power seems like it's lacking power. It is a 355 with blueprint h8002k with a xr276hr cam and 1.52. roller rockers and Holly stealth ram on top with 22lb injectors. Custom prom for the engine. 10.5 compression.
2k rpm stall
91 Camaro z28

What could improve to make more power I was thinking maybe porting the heads and upgrading the rockers to 1.6s and maybe bigger injectors aswell.
Has anyone ported h8002ks before ?
Any suggestions much appreciated

 

Seems like it would be running lean. Got any datalogs or wb readings ?

 

In the beginning I had a rich issue. I fouled about 3 sets of spark plugs but Scott fixed me up with a prom I got multiple datalogs saved from tunning it. Could i post a datalogs here? Or how would I send it to you?

 

You can zip a log and post it here

 

this is the last datalog i have done.
error code 21 has been fixed since this datalog

 

Any datalogs without error codes ?
did this effect your fuel trims ? Just curious

 

Theese are the previous datalogs and im not sure about the fuel trim scott has been doing all my tuning so far he has helped me out alot and fixed alot of problems with the rich issue.

 

looks pretty good, the lower rpm 1600 and less might want to lean it out a bit. having a wideband to see afr will get you the most out of the engine. don't see a whole lot of hp left on the table. you also might want to experiment with getting a burner and mess with timing.

 

Been thinking about setting up a afr gauge right now the car runs great just was expecting more out of all the mods. I appreciate your time and suggestions right now I have it set to stock 6 degrees. I've read some people get more power with advancing the initial timing.

 

It really depends on the tune. I’m betting Scott had advanced it in the tune already.

 

Do you think porting the heads or upgrading to 1.6 will unleash some power?

 

Get an AFR gauge and a proper dyno tune. 1.6 rockers aren't going to make significant difference. E-tuning is great to get something running and with many iterations can eventually get there for a mild engine but they will always be conservative. Also the tuner can't tell if you have mechanical or electrical issues contributing to the lack of power

GD

 

What rear gear ratio and where does it shift at? Stall seems a bit soft for 350 CID and that cam probably. I'm guessing headers and full exhaust to accompany that work too right?

I'd be thinking 22s SUPER SMALL for that engine. Comp's dyno of that cam with a Performer (non RPM) and Dart (World) S/R heads made 373hp. It may have been pig rich at the low end but I bet you're way out of gasoline. Those injectors are basically half the size of what they should be probably. Just because you have fuel on the low end doesn't mean you have it on the top end. If you have a stock fuel pump get an Aeromotive 340 and a hot wire kit or similar too.

Get a WB and hook it in to confirm but I'd put 50 bucks on you being out of gas even if you're running 70 PSI base FP which you're probably not.

For something like that you probably want injectors in the 42lb/hr ballpark. That'd give you fuel to 500hp with 80% duty cycle. You'd go static and hit 350HP with those 22s.

 

Agreed. Some 42's would be my choice also. My 42's are the perfect NA size. Idle has them about still well into their linear range so very easy to tune. I'm running Deatschwerks LS injectors in my FIRST intake.

GD

 

The injectors are a stock Corvette 22lb too injectors. The first step would be to probably upgrade to some 42lbs injector and also upgrade the rocker arms to some Scorpions 1.6 rocker arms. I do feel like the car bogs down alot in the higher rpms. I feel like I should be able to roast the tires with this setup but currently it's not roasting them until I'm really high in the rpms range but not for long before it gets some traction. The stall is just a standard cheap 2000 rpm stall. What stall would you recommend for this cam and what brand ? I'm looking to get the most out of this engine it's about 1000 miles so far on it.
what Injectors would y'all recommend?

 

No more engine power mods. You need to 1-Get some eyes on your engine (wide band) 2-Get enough fuel to your engine 3-Calibrate it correctly for that fuel.

At that point re-evaluate and consider more mods. I bet you're down 100+ HP with your current injectors and tune.

 

What wideband would y'all recommend? Where would be the best place to put the bung? I was thinking in the y-pipe. Would some 25lb injectors be my best bet or some 30lbs maybe?

 

At least 36lb injectors.

Wideband choice depends on your engine management. Find out which one is going to work well with your current ECM and whatever ECM you plan on upgrading to in the future. The LSU 4.9 sensors don't like to live when subjected to cold start moisture without direct ECM control (as factory ECM's have, or some standalone's with built in or CANBUS lambda).

The Innovate controllers are my choice as they report 14.7 on their 5v while in warm up mode. The AEM units have the 5v signal railed when in warm up which can be confusing and problematic for your management.

GD

 

AEM for the wide band. About 200 bones with a sensor. It's a gauge as well so that's handy for monitoring while running around.. It will also let you run a feed back into your ECU as well so you can use your regular narrow band O2 socket if you want. While it won't data log wide band AFRs in a standard ECU you can get an idea of what's going on by watching the gauge and if you upgrade to an EBL or aftermarket ECU you'll be able to pipe that data in.

If you wanted data logging back in the day without it being ECU bound you'd be looking at an Innovative LM2 or similar. Not sure what the hot thing is now though. The gauge will give you something to start out with in terms of seeing what the engine's doing.

Injector wise I'd be looking at 36es or 42s probably. Play with the numbers here but I'd want 450hp at the crank for that combo and 80% duty cycle. A bit lower won't kill anything. You will need a chip for it. I am surprised your tuner didn't say anything about trying to run 22s with that much engine.

Lastly, did you ever put an aftermarket fuel pump in? Something like a Walbro 255lph would be good or the Aeromotive 340. They're not pricey and are a drop in replacement. Bit easier said than done on a Camaro but you'll probably need it vs an unknown quantity like a stock TPI pump.

https://fuelinjectorclinic.com/flow-calculator

 

I took the car out for a spin today for some dataloging and noticed that the car doesn't even rev up to 6000 it's changing gears around 4500rpms. I did some 0-60 test and was getting around 7.2 seconds. What Rpm should the 700r4 be shifting at?

 

It is the stock tpi fuel pump I have a fuel pressure gauge and it all seems good. At first I thought I would need fuel injectors in the beginning but I figured if they were too small my tuner would recommend some bigger ones.

 

You need a wideband to know for sure.

GD

 

The governor on the transmission regulates shift points. You will need heavier weights or lighter springs or a combination of same to change the shift points. You can get a calibration kit and start playing with governor weights.

GD

 

Lighter weights cause later shifts. Heavier weights cause earlier shifts.

4,500-5,000 rpm is pretty normal unless they have a Corvette, LT1 or 2.8L V6 governor in it. My old 2.8 TBI GMC Jimmy shifted at 5,500 rpm on the floor.

Factory LT1 governor had the highest shift points at about 5,600-5,800. Might be hard to find one since they only made them for 2 years in the Vette and one year in the F-car.

I had a TPI Corvette governor in my G20 van. It would shift right at 5,200 rpm.

 

Oh yeah my mistake. Other way around for the weights. Lighter for higher RPM.

GD

 

True on the rarity but some grinder work and patience can get you a lot closer. The 2.8L governor was a great budget option back in the day to get those revs up some. I have one here that has lighter springs in it and doesn't have the chunks on the weights that shifts at 5600.

A good thread I found on the subject:

https://www.thirdgen.org/forums/tran...s-springs.html

A video I did on the weights. You can see the 2 little pips I'm talking about where it's spot welded on. I'd just drill right through those, pop off the weights and start there. Get a few nails that you can use for new pins and call it a day.

 

Hey guys , hope you can help me out. Finally got my 89 iroc z TPI running and I’m looking for some quick ways to add some power to it. Looking into cams, headers , manifolds but I’ve seen there’s debates between sticking with the TPI or going with the HSR . Anyone know what would be a good way to get some kick outta this thing.

 

Best to start your own thread. No one is going to notice you down here asking the wall questions in your neighbors basement.

GD

 

Ramirez,
The number one mod to do is headers. They make a big difference in performance and they sound killer. It was one of the first mods I did with my car and I noticed the difference. The HSR is great on the high rpms it flows well and can support alot of mods. That's the reason I choose the HSR over the stock tpi because it flows alot better past 4500rpms and with a cam and a good tune it will definitely wake up the motor.

Good luck with your build

Jonathan

 

So today I started grinding the weights to see if I could change the shifts and They were 14 grams stock and grinded them down to 9-10 since I wanted my shifting at 6000rpms but I kinda messed up the weights by grinding it flat and not leaving a point under the spring. After watching other videos and reading the fourms I realize I have to order the b&M kit now. I took it out for a drive and wot the engine would just redline not even shift unless I played with the throttle. But it definitely spun the tires alot longer than before. I truly appreciate everyone's help so far.