The Forced Induction VR6 thread

[Kevin Bacon 5]

Map 3 doesn't add up. No way a GT3076 can make 540bhp on a VR6 from only 16 psi. Not even a 35r comes close to that. You don't just jump from 380 @ 10 to 540 @ 16.

[dr_mat 0]

Looks like the scale has jumped by 100bhp/lbft in the third graph to me. You telling me it's suddenly generating 300 lbft at 2000 rpm on 3 psi boost? Not likely.. I suspect a lazy right foot on the brake pedal during run-down bumped the drivetrain losses calculation up..

[jamminvr6storm 0]

Map 3 doesn't add up. No way a GT3076 can make 540bhp on a VR6 from only 16 psi. Not even a 35r comes close to that. You don't just jump from 380 @ 10 to 540 @ 16.

 

Correct Kev - when I posted these graphs last time I did explain that the high boost map is 5% out (approx 30bhp)

 

Emeralds strandard rollering road software only go up to 400bhp, they use a different software set up to read higher power than that.

 

If you look at the power increase from 7 to 10psi (56bhp) then x2 for the difference between 10 and 16psi (112bhp) its running about 500bhp on the high boost map.

[Kevin Bacon 5]

Fair enough. Even 500bhp is a bit optimistic from 16psi. Sorry, not trying to be funny or have a dig. I really like and respect what you've done, I'm just trying to understand these big variances in power from our VRTs.

 

Stealth had the same problem a few years ago when their Dyno could only measure up to 250KW (340ish bhp). Anything over 340hp was open to a bit of creative tranny loss correction.

 

Since Vince installed his 600hp dyno, we're seeing some pretty consistent numbers from the VRTs he's mapped and 15 psi from a GT35R sized turbo on a standard engine sees around 420-430hp. Given you're running the smaller GT30, 70hp is a lot to find from less turbo flow, regardless of your bigger valves etc.

[jamminvr6storm 0]

I can understand what your saying mate but the 56hp gain from 3psi was measured on the standard rolling road software.... therefore I fail to see why 6psi wouldnt give a gain of approx 112hp. Does that make sense to you?

 

We both know that a GT3076 is capable of 500hp, as is a GT35 of 600hp.

 

I think we need to get this RR day set up!

[boost monkey 0]

56hp from 3psi..... hmmmm.

[jamminvr6storm 0]

56hp from 3psi..... hmmmm.

 

Lets say a standard VR makes 200hp.

 

Well Kevs makes 392 @ 11psi - therefore divide 192 by 11 = 17.45

 

56 from 3psi - same maths = 18.6

 

Not that much difference fella.

[Kevin Bacon 5]

I'm not questioning your numbers mate, just the amount of boost you need to see 500hp.

 

I'm not saying my numbers are right either by the way, but they do seem in line with other similarly spec'd engines, but there is no way mine would make 500hp from just 16psi.

 

You can't really apply a blanket 18.6hp per psi of boost, it just doesn't work that way. Turbo flow efficiencies change with rpm as the engine consumes more of the air. By that reckoning you're saying your turbo is capable of 665hp @ it's max of 25psi. Usually you would need a 1.06 housing on a 35R to see that hp, or a GT40R.

 

Shaun had exactly the same turbo as you, same intake, same cams, same 3" cat-less exhaust etc, but he got 400bhp from 15psi, which is about right for a GT30.

 

Still, it's all interesting debating material. It's what this thread is for :D

 

I reckon we should do this VRT dyno day and all run 1 bar of boost and see what numbers come out the other end :D

 

BTW, I'm not suggesting you are fibbinr or anything, I know you're not like that. I'm just perhaps a little suspicious of Mr Walker's dyno numbers, t'is all. There's no doubting he's done a good job of your mapping looking at those torque curves.

[coullstar 0]

This is the reason I put my original post up as there does seem to be a fair bit of variation between similar spec cars. Where are all the Stealth turbo conversion guys?

[StormchargedVR6 0]

 

Shaun had exactly the same turbo as you, same intake, same cams, same 3" cat-less exhaust etc, but he got 400bhp from 15psi, which is about right for a GT30.

 

 

I did find it hard to make out how much boost you would need for 500bhp, and its lot more then 16psi. you must have been running the GT30 at its limit?

need to do a RR day at JKM or Stealth

[Kevin Bacon 5]

This is the reason I put my original post up as there does seem to be a fair bit of variation between similar spec cars. Where are all the Stealth turbo conversion guys?

 

I think Greg Kirby's got a Stealth kit making 425hp from 1 bar. The turbo Vince uses is a T4, which flows about the same as a 35R. The normal Stage 1 boost pressure is 9psi, which sees 360hp, which is in the ball park of mine and Ben's at that boost.

 

The only thing I'm querying is the 500hp @ 16psi bit. Everything else seems on the mark.

 

But on the flip side, yours appears to be below par.....but then again, how do we know the dyno you used is accurate and ours are way too optimistic?

 

There's only one way to find out...... FIIIIIIIGGGGGHTT! :lol:

 

I did find it hard to make out how much boost you would need for 500bhp, and its lot more then 16psi. you must have been running the GT30 at its limit?

need to do a RR day at JKM or Stealth

 

I'd be up for a JKM dyno day. My car has only ever been on Stealth's rollers so it would be nice to see what it does on a different dyno.

 

Completely the opposite end of the country for Graeme though.

[big ben 10]

so when are we going to have this Rolling Road day then? i need it to be cold so i can get a few bhp more than last time :lol:

[StormchargedVR6 0]

I could arrange it with Kate @ JKM if enough interest

[Kevin Bacon 5]

Would have to be Feb/March for me when I'm back on summer tyres. Winters can't go over 115mph, which will be exceeded easily on the dyno :D

[coullstar 0]

Wheres JKM? I visit my brother in Poole a couple of times a year so I could save up for fuel and bring it down.

[boost monkey 0]

56hp from 3psi..... hmmmm.

 

Lets say a standard VR makes 200hp.

 

Well Kevs makes 392 @ 11psi - therefore divide 192 by 11 = 17.45

 

56 from 3psi - same maths = 18.6

 

Not that much difference fella.

 

I really don't think it's that linear. You have so many more factors to think about when you increase intake air pressure than just x times y. IATs for example.

 

But if I'm wrong, then fair enough :D

[big ben 10]

lets say second weekend in March then, will give people enough time to get stuff sorted and kev time to get his tyres sorted out?

[Kevin Bacon 5]

Wheres JKM? I visit my brother in Poole a couple of times a year so I could save up for fuel and bring it down.

 

It's the place that built Shaun's VRT, they're in Portsmouth I believe.

[coullstar 0]

Just along the road from Poole then. This could be feasible.

[StormchargedVR6 0]

March would suit me fine, im hoping to be over about then for UDs show :)

[Kevin Bacon 5]

Will you be running the R or just spectating :D

 

Do JKM have a good coffee machine? :lol:

[boost monkey 0]

Stealth had the same problem a few years ago when their Dyno could only measure up to 250KW (340ish bhp). Anything over 340hp was open to a bit of creative tranny loss correction.

 

There's only 0.745kW to 1horsepower, so 250kw would be ~190hp :scratch:

[wormy 0]

There's only 0.745kW to 1horsepower, so 250kw would be ~190hp :scratch:

 

Other way around, Mr. Boost monkey! :dorky:

190kw ~= 250hp

[StormchargedVR6 0]

Will you be running the R or just spectating :D

 

Do JKM have a good coffee machine? :lol:

 

Mite run it , we need at least 20 -25 people for this to happen

 

They always put good spread on mate :)

[coullstar 0]

Just read through Shauns build thread and the power / torque graphs are posted on this page - viewtopic.php?f=11&t=27296&start=270

If I read that right the diff between the ATW and ATF power is 65bhp with ATW figure of 336bhp. Isnt 65bhp loss a bit high, mine was only 39bhp? The ATW figure seems about right does it not? All these different dyno's seem to be causing the differences. :shrug:

 

A definitive RR day seems to be the only way to find out how we all perform, would still prefer Stealth though so I can be lazy and get my TC fitted at the same time :lol: