1.) What is value upgrading from the stock pistons with only 250whp. I know the rings don't like that much but can't you just install better rings? Stock pistons and some descent RODs and this could be a done deal. Am I missing something?

2.)What with the big(er) turbo why didn't you use the GT2560R to hit your goal?


3.)Reading this thread I have to ask why didn't you go with a supercharger instead of a turbo to avoid lag?

Yes.

because more exhaust energy would hopefully get the turbo spooling sooner. Are we sure that the 4% rule is a linear relationship to RPM? I seriously doubt it is.

The corrado made lots more power naturally aspirated in the lower rpm range than it did with the turbo and low compression motor.

1.) peace of mind when I'm at the track 4 hours from home
2.) Corky recommended it since its a track car
3.) because no one would sell me a mp62 with no electronics, and they typically don't make as much power as I want until they spin a high enough RPM to have reliability in question

My point being that spooling sooner is not going to radically alter that powerband in the example you gave. Not without changing the turbo. You are giving an example so extreme it has little bearing on your current setup. For what it is worth that car was not in anyways well sorted. 2.9 liters making that sort of power there is not reason for a powerband that peaky. There was one or more serious flaws either in the design or the execution.

Drive a 1st gen DSM, 7.8 compression. No lag.

See Foundsoul's recent dyno chart. His powerband is huge, with only 1600 cc's of fury to spool his 2560. You'll have 1900 cc's on a 2860. Should be comparable in terms of spool, but you'll have more power everywhere. You'll have a better head too.

PAT! - I'm kinda gonna call BS on the eclipse I've had both 6 and 7 bolt GSX eclipses 14b and t25 and they were both kind of dogs down low. Don't get me wrong they could get going and porting, upgrading piping, manifold and downpipe helped. But it still took a bit to get going from below 2500rpm. Once the motor was around 3500rpm a jab of the throttle would create a possessed monster I'm sure you know all about that. I miss those cars.... :sadwavey:

Miata is better though :)

even the newer evo's suck balls out of boost, and they're at 9.0. I'd like to know if anoyne has ever tuned an 8.6:1 motor to not drive like shit. I'm confident in my road tuning ability to make it work, if its possible.

Yeah, maybe "no lag" wasn't the right way to put it... but as a counterpoint to a powerband tripling in the span of 700rpm due to having 8.5:1 compression I figured it was the best (likely to be in the realm of experience of anyone here) example.

And for what it is worth, tuning eliminates that sluggishness...

Also, MKIV Supras have 8.5 stock... as do GENIII 3sgtes (MR2, Celicas). Neither of which are slouches.

Wasn't it earlier this month that said you didn't trust yourself to do any road tuning, for fear of messing something up? Not choosing correct AFR? Geez man...

I had a 88 300ZX Turbo. It was 100% stock. 8.3:1 compression and it spooled at 3500. With some aftermarket parts and a new ecu, it would probably spool closer to 2500. It made decent power before it spooled. I wouldn't say it drove like shit. The turbo could have spooled sooner.


How a car drives is not controlled by compression alone. 0.4 points of increased compression will not make a shit.

Playing with ms for a few hours last weekend inspired confidence.

Define "drive like shit". If after tuning the proposed 8.5 motor with a standalone you can't get to within 5% of a completely stock car you don't need to be tuning it yourself. And if you expect your off boost power with your turbo set-up to exceed the power it made NA than you have unrealistic expectations.

And it itsn't all about peak numbers, but throttle and transient response will all come down to the tune.

My turbo spooled to 12psi @ 4.4K

it now spools to the same at 3.4K. I shaved 1000RPM off the spool with exhaust and mild headwork alone.

and it's a 1.6L and has a bigger turbine than your 2860RS IIRC.

9.0:1?

who give's a funk?!

I'd like to know if people are getting results like this with low comp motors.

but the point here is I shaved that much off without changing my compression or spark map.

what turbine wheel do you have?

Hustler-read. http://www.musclemustangfastfords.co...tio/index.html

Using the 4% rule. Assuming you make 250whp with 9.0:1 ratio pistons.

9.0-8.6=0.4 This is the change in compression

.4 X 4%= .016 This is how much power will change.

1-.016= .984 This is your new power factor.

250whp X .984= 246whp with 8.6:1 compression. That's a 4WHP difference, which would be almost undetectable.

thanks, but I've stated countless times that I'm concerned with spool and not max output.

T3 stage I (journal) .48A/R. 58.xmm vs your 53.8mm turbine wheel and BBs.

And they will be linear. If you increase power X%, your spool RPM will drop X%. Do you understand these are related? That's the whole point of me doing that math is to show you that 1.6% change in power or spool isn't gonna make a shit. Hence, you should have kept the pistons you had.

yeah, I'm kinda kicking myself in the ass right now. I still have the quandry of running 2618 or 4032 alloy...wiseco or supertech.

i think you should buy a FM stroker built by them, with their FMII kit, installed by them and at full cost.

I agree.

+1

Maybe he should wait the 3 weeks get some nice custom 9.5:1's or 10:1's. Then his only trouble is the turbo he has may be a bit excessive. This may not effect spool but the car will be snappy off boost. You could also send out the head and get it ported. Between the two you would definitely have what you want.

+1 on the FM idea

Then to simplify things you should cut your losses and start saving up for the stroker kit from FM. If you still have aftermarket rods I'll give ya 100 for them.

go ahead and paypal the cash to me.

What's your paypal? How much to ship them? What brand are they?

just send the money. $100. Hold on while I set up a "new" account.

Not directly comparable, but my stock motored 94 (8.8-1) running a standard FMII (GT25) made 15 psi by 3100 rpm. 12 psi by 2900. I dropped from 3400 by spending some time on the dyno. Car has no cat, and a 3" exhaust. Compression ratio is a minor detail. Open exhaust and a good tune are much more important and make a much bigger impact on how the turbo will spool.

Any turbo car will feel like a dog off boost. Its because on boost is so much more fun. I can tell you that I RARELY experienced lag in my car. And that was usually a result of me being in the wrong gear.

When I drove around with my wastegate wired open I thought the car was broke. I was actually scared to take it WOT cause it just wasn't right....even though I knew in my mind I just lost 250% of the power on purpose.

I don't understand.

Yeah, we get that.

the car was broken, so you still shifted at redline instead of taking care of it?

wired open wastegate = 0psi = 90rwhp
non-wired wastegate = 13psi = 230rwhp

230/90 = 2.5 or 250% power loss.

I don't understand the context. I understand that an open wastegate means no postive pressure. I'm reading into the comment too much apparently.

yes. SpyHunter mentioned a turbo car being a dog off boost. i was saying without boost the car felt broked.

My dad had a customer once, he came in a flatbed, with his car on back, and there was a big ass hole in his block, and another in his oil pan. His wife pulled up in a separate vehicle shortly.
My dad said to him, "Gee there must have been some warning before the failure, perhaps a loud knocking sound." Dude responded with "Yeah there was." "What did you do?" my dad asked. The reply was, "So I turned the radio up." That's when his wife slugged him. Funniest shit ever.

lol. I had an xgf who used this logic. She totally destroyed a chrysler sebring in less than 2 years. Wrecked it numerous times, curbed int constantly, broke interior plastics, didn't even take it to the dealer for free oil changes, just drove it on (ballpark) 3 oil changes in 2 years. I felt bad for that car.

i've had both a 1g dsm and a 2g dsm, 7.8 vs. 8.5, more of a difference than you're agonizing about and really there's not much of a difference. seriously though with the gearing in the miata you won't have any issues keeping the 2860 on the boil. with good tuning and you're motor you'd probably have 12psi by 4000rpm with 5:1 pistons

Ask Jason Cuadra. He swapped out his stock 2000 motor (9.5:1?) for an 8.2:1 GTX 1.8 courtesy of Jay Kavanaugh (you know, father of the disco potato...) and with his own home-brew cylinder head work he GAINED spool.

Course he has the FM SBB (2554) so I'm not sure what more spool really means there.

I just jumped on the deal for the pistons *shrug*

with these little baby dick turbos, i wouldn't think spool would be an issue.. spool it, and crank the boost.. ;)

Wait the Evo 9's are ever out of Boost? Only if the owner is retarded and dont have Meth Injection. Both my friends Evo 8 and Evo 9 have MBC + Wb02 + Flash tune by Jester + Meth Injection = no matter what RPM they stomp on the gas and your pushed back into your seat like a mother... I dont know the hell your talking about when you say the Evo's suck balls out of boost due to the fact the only way to keep them out of boost is to baby the garbage out of them.

And if you have the $$$$ to own a evo and shit spend the extra like 2k to get a wideband a MBC a quick tune and some meth injection and if you don't you shouldn't be driving an Evo.

What the fuck are you going to be doing with the car that requires you know when boost hits, down to a 200-300 RPM range...

Its a track toy, not a god damn race car. right? These are small, rather little turbos...this is borderline obsessive paranoia. I could understand fearing blowing your shit up, thats not a fun thing, but obsessing over little shit like this? wtf?

yeah, I really need to chill out.

with as much thought and advice you have, its going to be FAST...I think your starting to rethink your every move now.

I want to build this fucker so bad. I've learned a lot from all the research and annoying questions. I'm still super worried about cooling in 100* on the track considering all the turbo race cars suffer from cooling problems. The supercharged cars don't for some reason. I'm thinking about getting a spare hood and cutting it up to suck air off the radiator, and a vent over the turbo.

You could always have a tune to run WI also to help keep intake temps down. Then work on custom underpans to keep flow up

water temp is my concern, not IAT. Hopefully the BEGi scooper does the trick...if I can manage to not rip it off the first time I throw the car off the track...which is about once per track day.