Should My Hks Gt-Rs Be Making Boost Earlier? (E85)

[LaurelPWR]

Just converted my rb25 s13 to e85. the car feels a lot faster but should it be making full boost sooner???

also puzzled at how boost and power comes on later than the bp98 .....

Has the following mods:

Standard rebuilt rb25

acl bearings

arp bolts throughout

tomei poncams

hks ex cam gear +8 i think

hks gtrs turbo kit on standard manifold,

custom japan made r32 gtr 6 throttle plenum

retains standard side feeds high flowed 740cc

greddy cooler

apexi induction kit and pod

turbosmart plumb back bov

3inch turbo back exhaust 100cell cat straight through to twin cannons

power fc

walbro 460

tomei fpr

koyo rad and greddy oil cooler

blitz spec r boost controll

excedy light flywheel

nismo 2way lsd

etc...etc..

the bottom red line in dyno 1&2 is the bp98 18psi

the middle pink line in dyno 1&2 is E85 on the same boost

the top orange line in dyno 1&2 is E85 20psi and some tweaking

dyno 3 is just differant boost settings after it was tuned obviously....

[RBrennan25]

What do you use the car for? If it's a daily made he backed off the spool time a little bit so you don't end up pointing the wrong way down the street after a round about?

It is still making more power despite less boost (to be expected with the e85). Maybe he was having traction issues, or clutch slip, or something similar. That turbo would come onto boost pretty freaking hard so did the tuner mention anything about that?

[Blackkers]

What do you use the car for? If it's a daily made he backed off the spool time a little bit so you don't end up pointing the wrong way down the street after a round about?

"backed off the spool a little bit" couldn't help but laugh a bit sorry mate.

E85 won't make the turbo boost earlier. It makes slightly more power for the same amount of air. Air is what spins the turbo though.

Should be about the same response wise just faster on boost.

edit: It looks slightly laggy for your set up though, I don't know what ramp rate the dyno operator was using. hard to compare that to the street.

You could try preloading the wastegate slightly or increasing the GAIN setting on your eboost controller

Edited March 25, 2014 by Blackkers

[RBrennan25]

Yeah certainly no mechanic

Basically what I mean though, the gain on the boost controller was turned down. I've heard of people with e85 and a gt ss and the word 'undriveable' was thrown around a lot, there was just too much torque and it drove like it was on ice.

[Ben C34]

Ask tuner why. Then you will know.

I wouldn't be happy with later spooling on e85 tune. Perhaps that's why the afr is not shown on the plot..... cos that's what you should be interested in, boost you can see for yourself on the road. (They don't tune the boost, they tune the afr and timing)

[Badgaz]

"backed off the spool a little bit" couldn't help but laugh a bit sorry mate.

E85 won't make the turbo boost earlier. It makes slightly more power for the same amount of air. Air is what spins the turbo though.

Should be about the same response wise just faster on boost.

edit: It looks slightly laggy for your set up though, I don't know what ramp rate the dyno operator was using. hard to compare that to the street.

You could try preloading the wastegate slightly or increasing the GAIN setting on your eboost controller

he could turn gain down on the boost controller to make it spooler slower couldn't he?

[Ben C34]

But why would he? That's stupid. Everyone wants early spool.

[LaurelPWR]

It's mostly a street car but fully equipped for drift...it's feels noticeably faster actually driving it on the street now (e85) then before on bp98.. I am now having even more trouble getting any good amount of power to the road without wheel spin (rsr semies)

It had year old good tyres on when was on the dyno....one did internally delaminate towards the end tho haha....

[Badgaz]

are you running stupid amounts of rear camber?

[Anfanee]

400HP and spinning wheels with semi slicks?

Yeah right. What suspension are you running or as said camber?

There is no way you should be losing traction with that power.

[discopotato03]

My experience with a GTRS on a 25 with E70 was it wanted to boost at 2200 revs and it felt like it couldn't breathe and did the ethanol "wobble" thing . I suspect that until the waste gate cracks open there is more air going in than the turbine housing itself can pass out so you get I suppose a locked up volume situation that the engine can't handle unless you back off or allow the gate to crack open at that point . You can drive a GTS25T up some surprising grades in 5th gear and silly low revs with a GTRS and E70/85 - if you can get the exhaust out through the combined housing and gate . If you go with the stay shut f**k you gate theory I think you'll choke the thing at low revs trying to get boost in when the engine can't really use it . The surge slotted compressor housing gets around compressor surge issues but you really need the gate to crack early and some electronic means of boost control to get adequate exhaust flow out of the engine .

Really people have to think about how much boost you jamb into an engine at low revs and how much it pays off - or doesn't actually . If you had a multi needle gauge showing boost and exhaust manifold pressure you'd be surprised what happens at times .

I never ran my GTRS on straight PULP but I'm sure the ahh hot side restrictions would have shown up as detonation and countering that would stop you forcing them into boost at real low revs . Ethanol is good stuff but I reckon it can resolve detonation issues in a setup that's trying to tell you it has a problem . I'm choking even if I'm not detonating ...

A .

[LaurelPWR]

400HP and spinning wheels with semi slicks?

Yeah right. What suspension are you running or as said camber?

There is no way you should be losing traction with that power.

It's a set up drift car it has adjustable and solid everything (bushes/arms) and a fair bit of body bracing/rollcage/heavy as swaybars and yes it runs a fair bit of camber can't remember exactly how much but I run shitty rotas 18x10 and 18x12...... Don't forget it's 400whp rb25 s13 mostly stripped out for weight reduction it had no problems spinning the semis befor e85

[LaurelPWR]

Also forgot to mention Matty put a sensor in the o2 plug on the dump and measured 4psi of back pressure at 20psi boost....

I'm installing a flanged allflow non cat and having smoke machine boost leak test done by a friend in the next few weeks and then back to Matty at pits for a re tune and to tune the throttles as well so well see how all that goes lol

[jake26]

Posting for notifications

[scotty nm35]

Also forgot to mention Matty put a sensor in the o2 plug on the dump and measured 4psi of back pressure at 20psi boost....

I'm installing a flanged allflow non cat and having smoke machine boost leak test done by a friend in the next few weeks and then back to Matty at pits for a re tune and to tune the throttles as well so well see how all that goes lol

Is the bong smoke machine under pressure? If not, don't even bother, just make a bung and cram some air into it. 20psi should do nicely if you can keep it in there.

[LaurelPWR]

Is the bong smoke machine under pressure? If not, don't even bother, just make a bung and cram some air into it. 20psi should do nicely if you can keep it in there.

Yeah man it is under pressure.... a friend at VAGarage has one he uses regularly to test and fix all the Audi/vw turbo cars he works on

[scotty nm35]

lol. VAG.

I still don't understand why you would need the smoke, I test intakes all the time and have no issue finding leaks with plain air, I just figured it was a way of charging more for what should take 10 seconds with a compressor. Try 40psi if you want to find them easier.

[LaurelPWR]

hahahaha vag.....nice

yeah your probably right about the smoke but its free and works a treat and i currently don't have a working compressor lol

[Badgaz]

some water and liquid soap in a spray bottle works mint too.

[LaurelPWR]

some water and liquid soap in a spray bottle works mint too.

Yeah tried this it does the job too but when you fit a set of gtr throttles to an rb25 there are a lot o extra vacuum lines under the plenum you can't get to so the smoke test is all round easier (: