Unreal

Definitely gained a ton at the 1/2 mile. Went 190.7 first take it easy pass. Then lost a headgasket next pass. Ohh well.

schpenxel

Hopefully it's a relatively easy fix. 190 is moving. Does that event do rolling starts or stopped?

Unreal

Rolling typically, but can do stopped if you want. That was a slow roll, take it easy pass with a passenger. Before anything over 188 was a solo run nailing all shifts. So 2+ mph, with passenger, taking it easy tells me it had solid gains.

schpenxel

Cool, wish the ones out here would let us do rolling starts just because I'm still on 05 rear so I'm pretty hesitant to launch much at all. Got beat off the line by an 80's BMW at the last one

Sounds like that intake is working well, and it looks nice

stevieturbo

I cant imagine you'd ever break anything launching on an airfield. And for distance stuff...no need to launch hard at all anyway...it might even be counter productive.


Hopefully it is just a gasket...when they go they can take a lot with them though.

Did it seem to free up more rpms at the top during the run ? ie were you shifting at normal points or did it feel like it wanted to go higher ?

Unreal

Pulled good and smooth. Not sure about higher, as things go so fast.

3rd run, shifted to 5th, lost power, car got all squirelly, almost **** myself sliding all over, slowed down, and white smoke. All coolant is gone. No other signs. Fires up, no noises, runs fine, just ate all the coolant. Best case gasket, then gasket+head. Worst case block got taken out, but oil is clean/clear, so no signs of that.

MTPZ06

Good to hear you saw gains...sounds like a few more mph is there when you get a chance to push it. Sucks you broke...hopefully just a gasket.

Unreal

I can't complain. Almost 30k miles on motor, heads been on for 7+ years. 100+ 1/2 mile runs. More beating on it than I could have ever imagined.

schpenxel

Yeah, you've def gotten some miles out of that setup. Way way more than most.

Think you'll do anything different when you replace the gasket if that's all it is or just replace it and go? Not sure what else you could really do honestly.

Unreal

Could do a ton. Change cam to a more modern grind for the new intake. Change lifters/soild roller. Do crower/etc roller rockers. Swap heads.

At least will get some different head gaskets if that is all it is. Was running the 4.2" bore LSX ones. Now with many more options that 4.125" bore would probably seal better anyways.

schpenxel

Yeah I just meant head gasket sealing wise. Ah well, hopefully it is that simple and you get some more miles out of that setup

Six-Gun-Todd

It's funny how that works actually...noticed the same thing at my mile event...hard leave netted negative results.

schpenxel

Interesting... I thought I could get an extra mph or 2 out of a decent launch but maybe not. I started in 2nd a couple of times.

Honestly I think a ZR1 transmission would help in my case.. crossing the line in 5th on a Z51 transmission sucks, it's such a huge jump from 4 to 5 and centri's drop off boost fast with lower RPM's

Pekka_Perkeles

Just out of curiosity...which one lasted longer: your latest WOT dyno runs or those WOT runs in this 1/2 mile event?

Pekka_Perkeles

Hm. Probably not because of overheating..

Pekka_Perkeles

Copper rings or pyramid rings of course.

But was it really as a result of added cylinder pressure because of better-flowing intake?

Well, I guess the answer is somewhere there on the logs of HPtuners, or in the broken hardware section. Which hopefully will be minimum.

Unreal

Half mile is way way way more. Full 0-190 pull deep into 5th compared to a quick 4th gear blast on Dyno.

Unreal

In about 90 minutes got heads ready to come off.

stevieturbo

A full 190mph pass for 1/2 would probably be in the 15-16s range. Obviously 1st to 4th probably not loaded as heavily due to traction issues.

Most single gear dyno pulls, maybe 3-4s ?


Shift at 7k and even those ratios should work well. I had a 0.74 5th and 3.27 rear on my car ( non vette ) and with a typical 25.5"-26" tyre could easily hit 200+mph in 5th ( standing mile about 8 years ago for me )
Yes there was a drop of rpm from 4th to 5th but it was still well on the power....but also not too much power that it broke the tyres free, and having a single gear that can take you all the way to big speeds is a good thing.
As letting off to make another shift at say 180mph there's no doubt the car will lose a few mph during the shift.

Even the 4-5 shift at around 140mph, I lose 3-4mph during that shift alone. I'm sure more aerodynamic cars would lose less though.

But if there was another 5-6 shift needed in that fixed distance when already moving pretty fast...it'd be hard to recoup the speed.

That's why auto's and certainly the likes of the DCT's in the GTR's are so great....they lose no mph on a shift so it's easier to optimise gearing and number of gears available.

Unreal

I'm sure zr1 5th would be huge in my car with the time I'm in 5th and power curve. Ohh well.