924Board.org

Euro924S2 · Joined: 06 Mar 2008 Posts: 215 Location: UK

I just thought I would update this thread now I finally have some dyno results.

So to summerise current setup:
1)100K mile completely stock Euro 931 series 2 block and head (CR8.5).
2) Eaton MP62 supercharger
3) 15 psi boost at 2.47:1 drive ratio (custom billet 140mm 6 rib crank pulley with fan belt over-drive)
4) 565cc Denso top feed injectors
5) Modified NA exhaust manifold to fit 931 head - otherwise stock 924 NA exhaust.
6) 951 FMIC (mounted low in 951 style front bumper)
7) Honda Civic Type R all aluminium racing radiator (55mm thick)
8 ) 944 header tank
9) Adaptronic 420C fully programable ECU
10) Crank and cam trigger wheels & sensors
11) Fully sequential fuel injection
12) Mazda (Miata) wasted spark coil packs. (distributorless)
13) Pre and post SC throttles with blow off valve
14) Custom cold air intake from 931 bonnet NACA duct
15) Custom intake manifold with 38 to 42mm tapered runners
15) Standard NA bell housing, clutch, torque tube and 5 speed Audi 924 'box

This all combines to give 232 bhp at 6.5k rpm and 231 ft/lb torque.

The current plan is to run this engine (after a winter break for the salty roads!!) for the next year, then swap in the 944 turbo 'box, brembo brakes and re-built engine which includes ARP bolts and cometic head gasket next winter.

I have photo's of the dyno graphs but I cant remember my photobucket login to post them up at the minute!!!

Happy New year, John.
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UK spec '83 N/A with 931 motor with Eaton MP62 'charger @ 15psi. EFI - 565cc inj. Standalone Adaptronic ECU. 951 FMIC. Ally rad. Twin throttle. Recirc valve. Custom manifolds and CAI. 232bhp

WEASEL149 · Joined: 19 Aug 2005 Posts: 595 Location: UK, Sheffield

That's pretty impressive - more power and torque than a 3.2 Carrera.

I bet it's nice to drive on our roads too with the low-down SC torque delivery.

My engine's in pieces at the mo. Hopefully I can get her back together with working EFI

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1979 UK 932

Euro924S2 · Joined: 06 Mar 2008 Posts: 215 Location: UK

Cheers buddy. Yeah, there's something very addictive about the low down grunt and the 'charger whine!!

Agree the powers pretty good but at the moment very little is optimised. Being an experimental engine, I've not dedicated much time on porting the various components and certainly there has been no polishing!!! Simply adjusting the tappets prior to the dyno run would have been a good idea!! Go knows when they were last looked at!! It's for this reason I'm delaying fitting the new engine - better to take my time prepping everything properly so the swap is less rushed. I rushed this setup to get it running before it was too late in the show season.

Back to the power though, it's the cars original low weight compared to safety featured modern cars that helps big time - 205 bhp per tonne is equivalent to some pretty sweet cars like the 300bhp Focus RS and current Boxster S!!

Best of luck with the EFI - I'm the recent proud owner of a new TIG welder so if there's anything you need help with then I'll do what I can! I'm practicing ready to make a new aluminium inlet manifold - I recon I can remove 40 - 50kg under the bonnet by swapping steel components for ali, shrinking the washer bottle and swapping the firewall heat proofing for a modern light weight version - it's tatty anyway so easy improvement when the engines out. Fuel accumulators going in the bin now too since not needed for the EFI.

Cheers. John.
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UK spec '83 N/A with 931 motor with Eaton MP62 'charger @ 15psi. EFI - 565cc inj. Standalone Adaptronic ECU. 951 FMIC. Ally rad. Twin throttle. Recirc valve. Custom manifolds and CAI. 232bhp

kcoyle · Joined: 15 Jan 2011 Posts: 712 Location: Long Island, NY

Slightly off topic, but are those lo profile pop-up headlights you made too?
I had a set on my old miata and I thought they were the shiznit.
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1982 931- Stock with MBC at 8psi

Relax, all right? My old man is a television repairman, he's got this ultimate set of tools. I can fix it.

Khal · Posted: Sat Jan 14, 2012 6:21 pm Post subject:

Fantastic!

The lesson, kiddies? Crank the boost 50%, fuel-inject it and sort the intake and... VIOLA! 75% more power! No spaghetti exhaust necessary.

What've I been sayin' for years? It's all in the intake. Back me up, Min...
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'80 924 Turbo

Euro924S2 · Joined: 06 Mar 2008 Posts: 215 Location: UK

@ Khal, Cheers mate. Intake is indeed very important, and non more so than on a Roots supercharger. These chargers are well known to be very sensitive to pre-charger restrictions. I'm currently working on modifying the bulk head behind the charger to allow a smoother root for the incoming air. On the 231 bhp run, there was still a bit of squashing of the silicone elbow. I've now bought most of the aluminium i need to make a new inlet manifold and supercharger outlet manifold, which I'm going to spend much more time on to hopefully improve their efficiency. I've also bought another 951 IC which I'm going to mount a new end tank to, again to try and improve flow.

With optimised intake and 99 ron super unleaded fuel (231bhp was on 95ron) I hope to get another 30bhp by maintaining the torque curve to higher RPM.

@Kcoyle: Yeah, they are a self made kit, but ironically they are a copy of my brothers IL motorsport lo-pro's which I fitted to his Mk1 Miata (supercharged to 215bhp with Jackson racing MP45). Mine have been on for the past 9 years and I have HID units on both dip and main beam - they are awesome on the back roads !!!!

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UK spec '83 N/A with 931 motor with Eaton MP62 'charger @ 15psi. EFI - 565cc inj. Standalone Adaptronic ECU. 951 FMIC. Ally rad. Twin throttle. Recirc valve. Custom manifolds and CAI. 232bhp

Khal · Posted: Sun Jan 15, 2012 4:12 am Post subject:

Raceboy · Joined: 01 Mar 2004 Posts: 2326 Location: Estonia, Europe

Khal · Posted: Sun Jan 15, 2012 4:16 am Post subject:

Raceboy · Joined: 01 Mar 2004 Posts: 2326 Location: Estonia, Europe

WEASEL149 · Joined: 19 Aug 2005 Posts: 595 Location: UK, Sheffield

flosho · Posted: Sun Jan 15, 2012 9:07 am Post subject:

Imo, our cars use terribly low compression ratios compared to modern cars. With solid efi engine management a higher static CR like what raceboys n/a has is not even a concern.
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[This Space For Rent]

kcoyle · Joined: 15 Jan 2011 Posts: 712 Location: Long Island, NY

leadfoot · Posted: Sun Jan 15, 2012 11:12 am Post subject:

Yeah my various engines havemade similar numbers,
I do believe heat management is important; through coolant flow 83~85c, oil and air.
Compression can be increased along with advance for considerable gains,
Although a change in heads does summount to increased head flow.
10psi boost intercooled shoud net you 210/215bhp easily. After that the 10bhp/psi equation should apply provided the above is managed.
In regards to flow restrictions on sc's, ive never really understood the twin throttle setups, i think its a waste and just a flow retriction. It can help control tip in if your tune is fairly rough or you dont havean adjustable air byass solenoid. Blow through throttle is by far simpler and easier to tune.
I changed my 63mm intake for a 100mm tube and the difference was instantaneous.
I also think the m62's are too small the 1200cc blower i used for a mild conversion was nice but the 1400cc blower rc has is the ideal size.
Stu
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1981 ROW 924 Turbo -
carbon fiber GT mish mash
LS1 conversion in progress...

Raceboy · Joined: 01 Mar 2004 Posts: 2326 Location: Estonia, Europe

Additional throttle body is beneficial on turbocharged engines as it acts better than BOV and eliminates the necessity of one at all. '80's turbo era F1 engines utilized pre-turbo throttle widely.
I'm planning this next winter if I keep my Gulf by then.
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'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold

'84 924, turbocharged, sold.
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