The bondo left on the firewall after blasting was from a serious nitrous meltdown back in 1991 where I burnt the entire engine compartment out of the car and warped the firewall. Damn near lost the whole car!

 

It's about time you updated this. We were starting to think you didn't love us anymore.

 

No shit Hillbilly. So I turned it up to 13 lbs last night in the cool air and what that created....is a car (on nothing BFG street tires) that breaks em loose hard at 65 mph and smoked em to almost 90 before I let off. Damn I like this destroker motor!

 

Video or it didn't happen.

 

Well I think im a queer because I decided on a whim to take it to the dyno and.......didn't video a damn thing. It was yanking 12.5 lbs boost, 18 degrees timing, 90 degree shop temp and it made 555 whp. The turbos are pretty much crap on this combo as even with a WOT hit at 2000rpm in high gear, it took all the way to 5100 rpm to hit 13 than fall to 12.5 so torque was a dismal 477 ft lbs.

I tried a little experiment which I think is a failure. Its a Comp 228r cam with 588 lift and I had some 1.8 rockers laying around and slapped em into the buildup. Total lift is 622 but I think the ramp speed is too excessive since it seems to lose valvatrain stability around 6200 rpm. All the yummy goodness of a short stroker is lost because it was fluttering and sounding unhealthy at 6400 rpm where the power was still on the rise. Not bad for a first shot though!

 

Dyno sheet. Looks like a Honda 4 banger dyno graph with only 250 hp at 4 grand. LOL. Might have went a little too big on the turbos! But I tell ya last night in the cool night air that sucker laid rubber in 2nd from 65 to 90 mph like a dirty bitch! It is a fun motor but needs more work for a street car.

#ad

 

I wouldn't give up on the turbo's, just needs a loose converter. Toss the 1.7 rockers back on and see what you can rev it to. Aren't those pretty aggressive lobes to start with?

 

Im not sure what the lobe profile is but I have a feeling its a pretty steep ramp. Today I ordered a trunnion upgrade for some stock 1.7's and also a set of 8 factory LS7 1.8 rockers. I think with the super low backpressure from the too big turbos I am going to try 1.8's on the exhaust only. If it still doesn't work ill go with a full set of tried and true 1.7 stockers.

What it has now is a set of cheap PRW screw in stud guideplate setup which in reality is a pretty stupid idea. Yeah its adjustable but why backdate a cool engine to older SBC technology with its stud flex and what not. Good old stock pedestal stuff is probably far more accurate.

 

I thought LS7 rockers werent interchangeable... Perhaps that was only on the intake side?

 

The exhaust side rockers are straight like older LS its the offset intakes that are LS3-LS7 specific.

 

Yes but arent the rocker stands further away from the valve on an LS7 head?

 

They might be but I bet the LS7 has longer valves too. We have had LS7's apart at the shop and the straight ones look just like ordinary rockers but honestly I don't know. They were delayed in shipping so tonight I decided to outfit the motor with all 1.7's with the Comp trunnion upgrade to at least get back to square one and something that works.

And work it does! I just datalogged a 2nd gear yank to the 7200 rpm limiter and GOD DAMN does that engine sound like pure magic at that rpm! It also will go 112 mph at the top of 2nd with a 3.31 rear gear and 27 tires. That's insane! Pulls pretty damn hard too but I think this destroker experiment is pretty picky about the combo, rear gears, stall and weight of the car to really perform right. I don't think its for everyone unless your an RPM freak because (at least with these big turbos) it leaves out a lot of stoplight fun and boost response.

 

Bingo we have a winner sir. I mocked up the 1.8's on a cathedral cylinder head today and found out GM approached the extra rocker ratio by lengthening the valve stem side of the rocker and moving the valves outboard like you stated. If a guy tried to run a 1.8 LS7 rocker on an older head, the rocker to stem alignment is pretty far off and if it DID run, it would still act like a 1.7 ratio.

 

So you gonna throw the 6.0 crank back in to get some low end back or are ya digging the crotch rocket power b band?

 

As mentioned, a looser converter will help, but I honestly believe a slightly shorter cam, with a bias to the exhaust might be the ticket. Something like a 220 - 230 112 installed advanced to around 108icl...
It would be worth a call to a real cam guy like Mike Jones, or Chris Straub. Guys like this truly understand the dynamics in the running engine, and can find significant gains.

 

I agree it could be better as far as street manners go. It would be the worlds best Bonneville engine. Short shifting it at 6000 it feels moderately fast but....you beat it to death and spin it past 7 grand and it feels up another 100 hp from 6 grand. I tried to upload a video of a fly by but it wont let me. Crap!

 

Lets try this. https://www.facebook.com/marty.stro...4311217/?type=2&theater&notif_t=video_comment

My facebook page. it uploaded there just fine.

 

That sounds good!

 

Thanks buddy! Tonight I relocated one O2 sensor from way down by the transmission to in the header just before the turbo to eliminate leakage fucking up the reading at the wastegate slip fit and boy did it clean up a world of problems! So I figured what the hell and I took it on a 130 mile round trip on the freeway tonight to check mileage. It spins 3200 rpm at 75 mph with the 3.31 gearset out back and even with perfect fuel control and damn near zero fuel trims it only got 15.5 mpg. Needs an overdrive dammit!

 

My DD gets 6-8 depending on how I drive it.


Cry me a river.