They say it cannot be done - 1000bhp Supercharged VXR8

They say it cannot be done - 1000bhp Supercharged VXR8

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R8VXF

Original Poster:

6,788 posts

114 months

Tuesday 16th February 2016
quotequote all
So this is the build thread for me to get my VXR8 GTS to a daily useable 1000bhp using supercharging rather than twin turboing. Why? Because I want to smile This is a long term build thread due to current time constraints from commuting and having to fit my life into weekends. I also want to do as much as possible myself, only employing the help of garages/mechanics where I do not have the tools or facilities to complete certain items.

So let me start with the current situation. I have a 2014 Vauxhall VXR8 GTS with a supercharged small block Chevy LSA producing around 580bhp. Utilising a stock bottom end and the stock blower, this is good for around 800bhp. To get to the 4 figure mark, I will be swapping out the stock roots 1.9l blower for a Whipple twin-screw 2.9l blower. Along the way I will be porting, changing cam and associated pieces, headers and exhaust etc. I will systematically work through the air flow path from front to back and will retune as appropriate.

I have a baseline dyno figure from late last year that shows as putting 478.1hp to the ground, and this was taken at Surrey Rolling Road on 19th December. The main purpose of this was to use Charlie's wideband O2 sensor to check that the fuelling was behaving as commanded by the stock tune. As you can see from the attached pictures, the AFR gets rather rich at the top end, but this is behaving exactly as expected and as commanded by the fuelling, so nothing seems to be amiss in the engine department. Good times.



Since that dyno session, I have adjusted the commanded AFR to be flat throughout the entire rev range, which should free up a few horses, along with raising the boost pressure entry point into power enrichment mode, which should save a bit of fuel!

I am now currently awaiting delivery of a Lingenfelter Performance cold air induction kit which should remove any restriction that the stock air box is introducing. http://www.lingenfelter.com/PROD.html?Product_Code...

According to some testing on an equivalent Roto-fab CAI kit on a ZL1 Camaro (same engine), this alone accounted for an extra 30rwhp! (Farcebook link: https://www.facebook.com/media/set/?set=a.10151547...

Partial list of mods to be done:
  • Valve springs
  • Injectors
  • Cam
  • Fuel pump booster
  • Headers
  • Whipple the st out of it biggrin


Edited by R8VXF on Wednesday 17th February 20:02

xeric

22 posts

100 months

Tuesday 16th February 2016
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Who said it can't be done?

Evolved

3,554 posts

186 months

Tuesday 16th February 2016
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With enough money anything can be achieved, depends on how deep your pockets are.

anonymous-user

53 months

Tuesday 16th February 2016
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Lovely, looking forward to watching this one.

RenesisEvo

3,602 posts

218 months

Tuesday 16th February 2016
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R8VXF said:
Since that dyno session, I have adjusted the commanded AFR to be flat throughout the entire rev range, which should free up a few horses, along with raising the boost pressure entry point into power enrichment mode, which should save a bit of fuel!
This isn't something I know a lot about, so feel free to tell me I'm wrong. I thought the reason why the AFR drops, i.e why the ECU chucks more fuel in than necessary, at higher engine speeds/loads (presumably the trace is at WOT) is to cool the combustion chamber, to prevent pre-ignition (knocking/detonation) causing uncontrolled combustion, which leads to big pressure fluctuations that can break pistons and blocks. So by holding stoichiometric right to the top of the rev range, yes you save fuel but you might also risk knocking - unless you're managing cylinder temperatures in another way, or I've missed something?

R8VXF

Original Poster:

6,788 posts

114 months

Tuesday 16th February 2016
quotequote all
xeric said:
Who said it can't be done?
Quite a few people are adamant that 800bhp for a valley blower is the useable limit.


RenesisEvo said:
R8VXF said:
Since that dyno session, I have adjusted the commanded AFR to be flat throughout the entire rev range, which should free up a few horses, along with raising the boost pressure entry point into power enrichment mode, which should save a bit of fuel!
This isn't something I know a lot about, so feel free to tell me I'm wrong. I thought the reason why the AFR drops, i.e why the ECU chucks more fuel in than necessary, at higher engine speeds/loads (presumably the trace is at WOT) is to cool the combustion chamber, to prevent pre-ignition (knocking/detonation) causing uncontrolled combustion, which leads to big pressure fluctuations that can break pistons and blocks. So by holding stoichiometric right to the top of the rev range, yes you save fuel but you might also risk knocking - unless you're managing cylinder temperatures in another way, or I've missed something?
The mixture doesn't need to be that rich. 12 is perfectly fine at current levels, when boost increases I will richen it up a bit though.

eliot

11,365 posts

253 months

Tuesday 16th February 2016
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Good luck - but I dont think it will happen with your proposed approach.
Stop wasting money on cold air intakes and spend some more time researching and amassing a decent budget. Things like LSX block should be on your list - or just call peter knight for an ouline budget idea.

Edited by eliot on Tuesday 16th February 21:02

S800VXR

5,876 posts

199 months

Tuesday 16th February 2016
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Have you asked Harry Oz or Jez how much they have thrown at their cars to get that power level... It's big money!! (Far more than yr car cost to buy.)

Fair play for wanting it but you will need allot more than a 2.9 I'd suggest and everything else down stream will need work or your gonna be putting prop shafts through the floor when they break.

Get a trip in Harry's to see if you think it's worth the financial commitment unless you have allot of spare change burning holes in pockets. I've been in both and their fast but not earth shattering compared to something like the SVMS R34, just because the platforms (Ro of VXR8) are just not ideal.

PhillipM

6,515 posts

188 months

Tuesday 16th February 2016
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It's loosing 100bhp from the fly figure at the minute then?

Seems a mite excessive...

SonicShadow

2,452 posts

153 months

Tuesday 16th February 2016
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That's about a 17% drivetrain loss, not that unreasonable really.

anonymous-user

53 months

Tuesday 16th February 2016
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Are we talking a "real"(stabilised engine dyno) 1000bhp or a "i got a 1000 brake number on my chassis rolls print out" 1000 bhp? Big difference!

Rensko

237 posts

105 months

Tuesday 16th February 2016
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That's huge power. Try reading up on some of the Aussie publications regarding big power mods to Commodores etc...

And mine only had 200bhp - albeit a 3.8L 1995 POS!

PhillipM

6,515 posts

188 months

Tuesday 16th February 2016
quotequote all
SonicShadow said:
That's about a 17% drivetrain loss, not that unreasonable really.
I'd say it is at that power level. I'd expect it on something with much lower power that looses a lot from fixed losses.

R8VXF

Original Poster:

6,788 posts

114 months

Tuesday 16th February 2016
quotequote all
PhillipM said:
SonicShadow said:
That's about a 17% drivetrain loss, not that unreasonable really.
I'd say it is at that power level. I'd expect it on something with much lower power that looses a lot from fixed losses.
TR6060 gearbox through a 9.5 inch diff. 15-20% loss is standard through this transmission. 576bhp is the factory rating, 476 is the rated figure at SRR through the wheels. I will take 800 to the wheels as the figure for 1000 at the fly.

R8VXF

Original Poster:

6,788 posts

114 months

Tuesday 16th February 2016
quotequote all
eliot said:
Good luck - but I dont think it will happen with your proposed approach.
Stop wasting money on cold air intakes and spend some more time researching and amassing a decent budget. Things like LSX block should be on your list - or just call peter knight for an ouline budget idea.

Edited by eliot on Tuesday 16th February 21:02
Shame you know nothing.

@S800VXR - Yes, I speak to J quite a bit and know what he has spent. No-one has tried my current approach, so should be fun biggrin

PhillipM

6,515 posts

188 months

Tuesday 16th February 2016
quotequote all
I don't loose that much power through an old transaxle with a massive 5.85:1 diff, high angle CV joints and Mud Terrain tyres....

R8VXF

Original Poster:

6,788 posts

114 months

Tuesday 16th February 2016
quotequote all
PhillipM said:
I don't loose that much power through an old transaxle with a massive 5.85:1 diff, high angle CV joints and Mud Terrain tyres....
You didn't loose anything.

R8VXF

Original Poster:

6,788 posts

114 months

Tuesday 16th February 2016
quotequote all
Max_Torque said:
Are we talking a "real"(stabilised engine dyno) 1000bhp or a "i got a 1000 brake number on my chassis rolls print out" 1000 bhp? Big difference!
800 to the wheels should be about right Max. As measured at SRR. If you pay to take the engine out and get it tested, jobsagoodun wink

PhillipM

6,515 posts

188 months

Tuesday 16th February 2016
quotequote all
R8VXF said:
You didn't loose anything.
Be some bloody warm components and tyres if they converting 100bhp into heat....

R8VXF

Original Poster:

6,788 posts

114 months

Tuesday 16th February 2016
quotequote all
PhillipM said:
Be some bloody warm components and tyres if they converting 100bhp into heat....
Yup, that is why the diff has its own oil cooler.