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Maxing out with 12.2:1 AFR from 6500 RPM onwards isn't what I call a HUGE problem as long as the EGTs stay cool, and cool they did stay. Next time I see you Ross, you'll get the 730cc treat and a wee bit more boost
Cheers,
Mihnea
'98 Silver Grey 2.7T S4, dual 2.75" turbo back exhaust with no cats, FMIC, BIG injectors, 10 Bar motorsport fuel pump, modded RS4 turbos, tubular exhaust manifolds, custom intakes, RS4 MAF, Bilstein PSS9, H&R ARBs, 19" BBS CH, custom remap, 511 BHP/505ft-lbs
Interesting spec you have there.. I'd be very interested to hear how you've been finding it, if you had any problems similar to mine and if so, how you fixed them!!
Torque was a little 'unsettled' - it spiked to 585nm, but generally wasn't over 530nm. I'ts lower than I expected, but the torque doesn't drop below 500NM till around 6k-rpm, hence the high HP. I'd guess that the turbo could therefore be suitable for stock rods, it's right on the limit but not really over it. But i suspect that a boost spike would be making banana's out of them.
Hi Ross
Same sort of problems i put a spacer under tranmission mount to raise engine to get hot side of chassis , Problems with surge also , now i,m try to build a good filter arrangement
i will post some pic,s
Cheers Wayne
Here's the dyno graph for the first run; scale is ft/lbs and HP (the major lines are 50 intervals and minor lines 10 intervals). x-axis is 800rpm increments.
Note the spike; you only notice this really in high gear/high load when the turbo has chance to spool up quicker than the engine can cope (this is surge?). Unfortanately I don't have any other graphs, when i get chance to have the map tweaked then I'd like to get another run with boost on it. In-car the gauge was showing 1.8bar peak, and fluctuating a little, which it doesn't do on the road!
Fluctating boost gauge is usually down to a boost leak in my experience. Mine used to do it before the overboost protection cut in when I had 1/2 and IC O ring!
When on the RR, I did notice on mine that there was no clamp on the reference boost line. If this was the same throughtout the cars then this will have caused a boost leak but I'm not sure how noticable. He also didn't re-fit the line correctly (forgot my fuel line clamp) after the run, as I found out when investigating some overboost protection problems the day after the RR day. A couple of cable ties later and the boost leak was gone, as was the overboost protection.
Just my 2p.
Cheers'en, AndyC
1994 ABY Coupe - Projekt Alpinweiss
Ross, the dyno graph is very interresting, but I lack a reference point for the x axis. Maybe you can tell the rpm for the major line left or right of the torque peak, then I can compare your data to my other collected data.
Impressive fat torque profile, but I don't like the look of that boost spike either...
I've just skim read this entire thread - what is the hot side of that turbo ?
I would also recommend 42 or 45lb injectors... I'm a bit surprised the 37lb'ers go this high but that is the benefit of 4.2FPR of course Takes you to approx 44lbs/min which translates to ~415bhp at 80% duty cycle using rules of thumb. I love it when the numbers line up with reality !
Some more injector headroom should indeed give you more power at the top end on the next mapping sesh I reckon !
Thanks for the replies - I'll try and answer a few questions:
Regarding the x-axis, it's an odd scale, the line the power curve just crosses is 7,200rpm - the left side of the graph is where it starts (0), i've just missed the first 100rpms off...
Spool-up is very quick, to say what max boost is would be hard, as once it kicks in the revs climb so quickly! With the spike, it throttles back a little, so I don't see it in full till about 4,000rpm. But that said, I did a 3rd gear pull last night from about 2500 and she didn't spike at all - well it was like it 'rode it through - i saw 1bar just after 3,000rpm and she maxxed at 1.8bar by about 3,500rpm. It was quite mad I try to avoid heavy throttle below 3,000rpm as I'd rather avoid the spiking as well which only occurs it seems if you floor it low enough for boost to rise to quickly/too little revs.
Johan - I'd be interested to know what other numbers you have, that I could compare too also? One reason i wanted to do this project, is that it seems hard to find a reference for this set-up so I figured what the hell, if I do it then at least others will have an idea of what to expect!
Paul - god knows what the hotside is, but its freakin' huge. I wish I'd taken some pics of it. I assumed it was K26, but it's fatter (found that out when the downpipe was pushed back about ~6mm! and Mihnea said it flowed alot better as there was little backpressure even at high rpms. It was stamped 'Garrett'. Bigger injectors will be interesting, as mihnea was being conservative with that limitation in mind - not sure if my trustee 5-speed will like it; guess a 6speed converion could be a project for the next garage meet What do think about the lower torque levels? I expected 400ft/lbs (ok it hit 430, but that was a spike) but it was more in teh 380 range... perhaps where it throttles back after the spike keeps it low, as there does seem to be a bit of a 'rollercoaster' effect with the torque curve right there.
Paul - god knows what the hotside is, but its freakin' huge. I wish I'd taken some pics of it. I assumed it was K26, but it's fatter (found that out when the downpipe was pushed back about ~6mm!
The hot side is pure Garratt, just machined for the stock fitment.
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