Modifying/Improving the 924 Turbo

[AlpineTurbo]

It is good to see that you are keeping faith in the project Steve, on such a great example of the car as well!

Regarding your oil separator do you have a drain going back to the sump or is there a drain bolt at the bottom of the tank?

[Carrera RSR]

It is good to see that you are keeping faith in the project Steve, on such a great example of the car as well!

Regarding your oil separator do you have a drain going back to the sump or is there a drain bolt at the bottom of the tank?

Yes and yes. It came with a drain bolt. I fitted a barb fitting and plumbed it back to the existing drain pipe to the sump.

Engine build now on hold as the US supplier who stated they have stock of HG's now tell me it's coming from Cometic, therefore 2-3 weeks waiting.

[Wes]

Engine build now on hold as the US supplier who stated they have stock of HG's now tell me it's coming from Cometic, therefore 2-3 weeks waiting.

Forgot all about this thread.
I'm in the same boat if it's any consolation, waiting on a copper Cometic.
I don't think there's a way round it unfortunately as they all seem to be made to order for the 924.
Resisting the temptation to install the OEM gasket is gonna be difficult as this is a big hold up for me now - I really need the long block in-situ to progress much further.

[nicksonmsport]

good stuff, shame to hear you have to wait so long for parts which are supposedly in stock!

i was looking on mittlemotor the other day and they have stock of main bearings which were nla for a while which is good to see!

be interested to see how yours in coming along wes!

[Carrera RSR]

Mittelmotor do indeed have bearings. As do EBS Racing in the US. Mittelmotor also have stock Cometics but at £160 vs £100 from US. But at what cost for the wait? Have a new Goetze HG which I bought first. Thankfully it's too thin for my CR otherwise I'd be installing it! Still, I've got a new headlining and Zeitronix data logging sensors and system to install this weekend, so no shortage of things to do. Could also fit the LSD box I got from you Nick?

[Carrera RSR]

Frankenstein lives again. Darkness fell too soon tonight but at least I have had it up to temperature for 15 minutes. A couple of evenings fettling and it should be back on the road for the weekend

[DarrylH]

Great work Steve! Nice to hear you'll be enjoying it soon

[Carrera RSR]

Did a 250 mile round trip last night and the engine purred away like a dream. Some quick scores on the doors of average results of the Zeitronix datalogging I have installed. Ideally I could do a sense check on numbers (chime in from Jon M would be appreciated!) from anyone with more engine tuning knowledge. The car feels super lively and the butt dyno is very happy as is but engine safety is paramount as ambient temperatures are only going to get warmer from now on. It was tough keeping the car under 80mph last night and only the lightest prods on the loud pedal saw a needle heading the into the wrong territory!

Cruising 2-3000rpm
AFR = 14.5 - 14.7
EGT = 750deg
post turbo = 40deg
post IC sub 20deg
Ambient = 16deg

Light boost 3-4000rpm 0.1- 0.3 bar
AFR = still 14.5 or at least low 14's
EGT = 750-800deg
Post turbo = 50-60deg
Post IC = 20ishdeg

Short full boost/WOT through gears
AFR = 10 - 10.5
EGT = 800deg
Post turbo = 80-90deg @ 1.16bar
Post IC = low 20's
Ambient temp 12 - 16deg

A full WOT pull through 3rd, 4th and 5th up a mile long+ hill hitting 5,000rpm minimum on changes
AFR = 10 average
EGT = 850deg
Post turbo = 110-120deg @1.16bar
Post IC = 28deg
Ambient temp circa 12deg

On the long pull up the hill I thought I heard some signs of very light knock (over sensitive ears and no sound deadening!). My knock sensor is out for repair so didn't have this set up. Ignition still set at 33deg from 5000rpm so may need to pull the timing a touch as well as maybe limit the boost as it appears over 4000rpm if at all. Any observations in the numbers? Plan is to have a dyno session in the very near future to ensure all is safe for the Summer.

In addition a number of my previous problems with the last head have now gone away. No more coolant pressurisation or heavy crankcase breathing. Cooling is well in check despite/due to reconnecting the cabin heater. It was nice having heat again on last nights drive home.

[jmgarage]

Hi Steve,

Those are not bad numbers for this stage in the game.

Yes a bit rich when on full boost, which on the one hand is safer than lean, but in the bigger picture will be pushing up your egt's, pulling some ignition might also push up EGT's, so you have a bit of a dangerous choice to make with pulling back the fuel or reducing timing advance.

You might even find that the knock you heard could have been EGT related, so pulling some fuel or even adding some ignition might actually help with that, but take really careful small steps there! But certainly try some less fuel and more timing, as non intuitive that might seem.

You are right to worry about warmer weather coming, looking at your data your intercooler certainly does not seem to be heat soaking at the moment, but you need to watch for that as the weather gets warmer, if that happens I have an experimental intercooler which may help, but I might be tempted to add a water/methanol injection system between the turbo and intercooler as well as another stage between the intercooler and the throttle body which may never cut in, but will be there just in case, I have something in mind if you are interested, but your injection system being a non intelligent system, you need to keep the parameters within a set range as closely as you can and the weather is going to be something out of your control, so some intelligent active measures to try to compensate for that would be a good idea.

I would recommend trying to keep your EGT's to no more than the 850 degrees you are seeing now, ideally a bit lower than that, but 900 would set off alarm bells with me.

What fuel were you running?

What spark plugs are installed? It might be interesting to see a picture of the electrode tips directly after a long hill pull like your last one, from that I might be able to read a little more what your engine is doing and if a cooler or hotter plug should be used.

Well done though, would love to know what power you are putting out now! I think there might even be scope for 1.4 Bar with some fine tuning and water injection from these early figures.

[Wes]

Looking tip-top so far Steve. I'm also curious to see what power the engine is making now you seemed to have sorted your head and head gasket issues.
Also interested to see when the standard fuel system reaches it's limits.

Need to take a day off work so I can reassemble the head, fit it to the block, and drop the whole lot in the engine bay. I'm refraining from posting pics until the engine is in situ with at least some of the modified parts fitted up.

I've not posted an update on here for a while but suffice to say my build has become a bit ridiculous, OTT, and overly-complex. Not good really, but will be on the off-chance it actually all works lol!

Now waiting on a charge cooler arriving from the USA - just hope it actually fits hehe.

At least I can test everything on this first engine before I use the 'built' forged bottom-end.

I now have the latest VEMS ECU in hand with 2 x knock channels and 2 x EGT built-in.
Also have the block and head modified for a split GTR style coolant system using 2 x Kolbenschmidt Pierburg electric water pumps, with 2 x bespoke PWM controllers, 2 x radiators.
2 x Turbosmart 40mm wastegates to go with the split pulse manifold and twin scroll turbo... what an idiot I am

[Carrera RSR]

Looking tip-top so far Steve. I'm also curious to see what power the engine is making now you seemed to have sorted your head and head gasket issues.
Also interested to see when the standard fuel system reaches it's limits.

Need to take a day off work so I can reassemble the head, fit it to the block, and drop the whole lot in the engine bay. I'm refraining from posting pics until the engine is in situ with at least some of the modified parts fitted up.

I've not posted an update on here for a while but suffice to say my build has become a bit ridiculous, OTT, and overly-complex. Not good really, but will be on the off-chance it actually all works lol!

Now waiting on a charge cooler arriving from the USA - just hope it actually fits hehe.

At least I can test everything on this first engine before I use the 'built' forged bottom-end.

I now have the latest VEMS ECU in hand with 2 x knock channels and 2 x EGT built-in.
Also have the block and head modified for a split GTR style coolant system using 2 x Kolbenschmidt Pierburg electric water pumps, with 2 x bespoke PWM controllers, 2 x radiators.
2 x Turbosmart 40mm wastegates to go with the split pulse manifold and twin scroll turbo... what an idiot I am

Turbo Nutter Barsteward comes to mind!!

[Carrera RSR]

Thanks Jon, for the comments.

I have now fitted a new ally rad and fresh dionised water/water wetter mix, fresh oil, fresh ITG air filter cone etc. etc. and doing a few miles to ensure its all buttoned up nicely. Next job is to book a dyno session and fettle to make sure I'm getting the best with what I have now and its all safe for Summer.

Have done lots of full load pulls in all gears and 0.9 to 1.2 bar and I'm not 100% confident I am completely knock free when at 1.2 bar. I am going to pick up a Phormula Pro with det cans tonight which plugs into the KS-4 so I can listen to for any events in conjunction to what the KS-4 is displaying. These engines are quite noisy to the naked ear and to the knock sensor. So det cans will help.

I have had some suggestions from Mittelmotor that supplied the dizzy that I could potentially add a degree or two into the timing, which is currently at 23deg at full load and go up to 25deg. I have two maps in the dizzy so I can run concurrent pulls with and without the increase/decrease in timing with a push of a dash button. Other suggestions were also lean off WOT to 11.5 - 12AFR and keep EGT's below 800 ideally but up to 850 is just OK. Most definitely keep away from 850-900!

Other than this i am enjoying driving it again

[Wes]

So, I'm going to try to update this thread as to where I'm at 'modifying' my car - mainly in photo format

First pics are regarding the coolant system. I've copied Porsche's lead and almost but not quite split the coolant system into 2 circuits - one for head, one for block like the GTR's.
2 x Kolbenschmidt Pierburg electric water pumps from BMW's with 2 x bespoke PWM controllers:-

[Wes]

Large channels at the rear of the head are now blocked:-



2 vent holes drilled to free any trapped air:-



Rear head port opened out:-



To fit this:-



The head circuit will now pump water into the rear and out of the front of the head.
Front exit is a modified thermostat housing with a 40mm exit as you'll see in later photos.

[Wes]

I milled the innards of the mechanical water pump out so it now just acts as a water inlet manifold for the block:-



The water exits the block where the rear core/freeze plug used to be:-