E30 with SR20DET

[Jon_Bmw]

Looks good theo. A customer of mine has a GTR with 506 Wheel HP. It is so quick for what is essentially a road car with a different map and exhaust. It does make you involuntarily laugh every time you press the throttle flat down for more than 3 seconds.

I really need to come and see your SR20det at some point. I am probably at Brands tomorrow as someone from work is entering his first race after getting his ARDS license the other week. That must be a baptism of fire, he is about 39, so not as youthfull and foolhardy as us! He is racing in the Nippon Challenge I think. Loads of Jap stuff, so if you are bored and you pop up, you have my number.

[Theo]

Cheers Gareth, looks painfully slow on the video - it felt like I was going fast at the time!

The GTR is a serious weapon though I'm not sure how fun they would be on a track? Probably quite alot of fun I suppose, as you'd be pissing over everyone!

Would be good to meet up Jon, not sure if tomorrow is do-able as I had planned on a session in the beer garden. Is you 205 still going strong? Got any track days planned?

[Jon_Bmw]

Watch a video of a GTR in the wet with the traction off. It is a joke really, but probably amusing. I still think for a pound/performance ratio it is unbeatable. I'd still have a gt3 rs though.

The 205 is sat in my parents garage, with the sump off for around 11 months. Further baffling work(if not quite literally) has commenced VERY slowly. Car is now 18 miles away, so enthusiasm to work on it dwindles.I have just bought another mi16 one from a mate for £300. Hoping to turn a good profit and spend the money on the car or an ARDS test / harnesses / suit / helmet.

Should be doing some trackdays around June though, time willing.

No worries about tomorrow, I just thought i'd mention it as its been a long time and i'm not often down Kent way.

[Theo]

Cool. You fancy a go at Racing then?

Just had a look at the Brands Hatch site - sounds like there could be some good racing. Got any free tickets?

[Jon_Bmw]

I wouldn't mind doing some real amateur clubman type stuff. Just to say i've done it, and before marriage and kids probably catch up with me! You never know I might be OK at it, but I doubt it.

I have three tickets, but alas they are being used. They are support crew tickets, so some might be able to be /cough\ reused /cough\. If you are coming up, call me. My number ends in 518, if it is different or you have lost it, PM me.

[Theo]

Nice one - I'll be sure to give you a shout if I'm coming up.

Failing that, we should meet up at a track day soon. I want to do another one before doing a track day at Spa or the 'Ring later in the year. Still not 100% on why my engine was spitting a bit of coolant out of the expansion/overflow tank...

[GeoffBob]

Belated thanks for the response Geoff, another interesting read. The idea of running jungle juice is well and truly off the cards!

Put it this way Theo, if your pumps, lines, filters and injectors can handle the extra volume of fuel, if your engine, drivetrain and cooling system can handle the extra power, if your turbocharger can provide the extra air, if your brakes can scrub off the additonal speed, and so long as you can re-tune your ECU according to your percentage blend, then it might be worth looking at. I think you have made the right choice.

I've uploaded a crappy video from Snett, quite funny at the end seeing how fast the GTR is down the back straight. I was doing about 130mph into the braking zone, he was doing 159! I chatted to him afterwards and it turns out his car was a bit tweaked and had 650ft-lbs of torque

Indeed, that it is quick. 650 lbs-ft is around 900 Nm, which is double what my engine is pushing. Take two of his wheels away and we might have a fair fight

[Theo]

Annoyingly the GTR appears to be very good through the twisty bits as well, I wonder what sort of E30 would be able to hang on to a well driven GTR?

I'm at a very strange stage with this project now, the only things I have planned are boring jobs like tidying the interior wiring, getting the sodding tacho working (I suspect a transistor in the ECU is buggered which means that it's not outputting a tacho signal) buying a new fuel pump as my current one gets a bit noisy, buying a new bonnet which isn't so gnarly etc.

One thing I might work on is making an undertray from the engine bay to smooth the airflow under the car a little. No idea if this is worth doing but I feel I should be tinkering with something!

[gareth]

Annoyingly the GTR appears to be very good through the twisty bits as well, I wonder what sort of E30 would be able to hang on to a well driven GTR?

Well, i know mine can hang onto a badly driven one... but that's not saying much I'd suspect a E30 that would hold on would be a very special machine indeed

[Theo]

Donington

What a circuit! Had a superb day their last Friday on the full GP circuit on the warmest day of the year so far. Cloudless skies and only a handful of other cars made for a truly memorable day of driving, tempered only by the fact that my car fell foul of the Sound Nazis which meant I had to short shift all day. I still didn't get overtaken all day!! Good old SRE30.

I was running on a set of Dunlop slicks designed for a Radical so I was a bit concerned about how they would cope with a car twice the weight of what they are intended for. I had contacted Dunlop Motorsport who said there was no problem doing this, but I was still a little apprehensive after comparing the side wall stiffness to a saloon car slick. I ran them at 34psi hot ( to guard against excessive side wall flex, which probably meant I wasn't getting the maximum performance out of them.

Everything was getting a tad warmer than previous track outings, partly because it was a warm day but also because I found myself doing long stints of laps because the circuit is one where you really build up a rhythm. Check out the heat haze from my exhaust on a couple of the pics! Diff temp was just over 120 degrees C, Intake temp was about 51 degrees C. Even after a 2.5 mile cool down lap the wheel rims were still almost 90 degrees C which was hotter than I was expecting. Ouch.

[GeoffBob]

Smashing weather Theo. Makes a change to see the sky so blue, I think we must have inadvertently swapped countries as its cold and miserable down here at the mo.

Looks like you had a fantastic time, and you'll soon be off to the NÃaburgring iirc?

[Theo]

It really was a superb day, glad it wasn't wet as that would have made Craners Curves absolutely terrifying!

NÃaburgring is on the 18th July - I WILL take a video on the day so I can finally get some in car footage on here. Plenty of preparation to do before then, which no doubt I will leave to the last minute.

[Jon_Bmw]

That does look like fun. Intake temps seems quite high?? We have been getting (probably uneccessarily) concerned when intake temps on our engine dyno rose over 35 on a 4B11(evo x). We are endurance running it(120hours), and trying to keep a turbo engine cool in a cell is a drama I can assure you. I will never ever reccomend using a charge cooler to anyone. You can probably guess why.

Does the management retard the timing when it sees the intake temps that high? If it is running standard SR20(with a chip) it should do, but it might be worth checking that the lookup tables account for full throttle. Again they should, but a few management look up tables are ignored when flat on the throttle.

Edit: THe high intake temps could be the symptom on a turbo working outside of its efficieny range or an undersized intercooler. I doubt it is the latter as I bet when you bought the kit it had some 'Sic' mamouth JAP 'cooler. Time to get a mahooosive turbo?

Of course if you didn't know the intake temps there would have been no problem..... Remove the sesnsor.

[Theo]

Geoff made some very interesting points regarding intake temps back on page 19 of this thread. He suggested that intake temps in the inlet manifold which are 20 degrees above ambient are not excessively high. Bearing in mind it was over 25 degrees C ambient I wasn't too worried about a 50 degree intake temp - that was running about 1.1 bar of boost for 20+ minute stints.

The inter cooler isn't massive, and is only an ebay special so the core isn't as densely packed as it is on a high quality IC. You're right, the kit I bought originally had a very large intercooler, too big to fit to an E30 with any degree of subtlety. Saying that, I wouldn't be surprised if the turbo is working outside it's efficiency range - it's just a standard T28 (gt2560). Geoff and I have discussed the pros and cons of fitting a more manly gt2871r on his own build thread and that's the upgrade I intend on doing at some point. Just a toss up between boost creep on the smaller turbine housing version, or lag on the larger version.

With regard to the engine management, I'm not sure it does factor in intake temp actually. I don't recall there being an intake temp sensor as standard. I fitted one rigged up to a small LCD display, purely out of curiosity. I am running standard Nissan management with a Horsham Developments stage 2a chip. You probably know more about the engine management than I do (i.e. more than zero)

Get your bloody 205 working and bring it to a trackday or two!

[Jon_Bmw]

Well if it has no air temp(of any form), then it can't retard it, how retarded. Are the sr20 AFM or MAF, I really know very little about the sr20, I know the Ca18det uses a AFM as I have an s13 tucked away.

The HD chips were quite well regarded when I trawled the SXOC many moons ago, although our 260-270 spec (t28) CA18 always pinked a bit in 5th gear on warm days...perhaps it is related. That has a large front mount saab jobby, but ultimately not a brilliant intercooler. Or perhaps the HD chip runs too much advance to make some dyno graph look good down the pub.

I would still argue 50'C is too much IMO. As we were running an Emerald on this 4B11 we spoke to Dave Walker about our inlet temp concerns and asked what he felt was the limit, or where he would stop mapping till it cooled down. He said about 40'C.

Interestingly the ignition corrections are pre set on the Emerald to start at 40'C. For example you would have -1 degrees igntion at 40'C and -3 at 50'C. It interpolates between the sites like most mapping software and thus at 45'C you would have -2 degrees ignition.

Definately worth speaking to some Jap experts, i.e not me.


The 205 isn't a million miles away, but I bought another mi16 one that needs work...

[Theo]

Interesting, I shall add intake temps to the list of things to worry about! The SR20 uses a MAF btw.

I think a wideband gauge might have to be the next purchase.

[Jon_Bmw]

Whatever you do don't fit an oil pressure gauge, all you'll do is watch it and shunt the car off the track!

I suspect the MAF will sense the charge temp and alter the maps accordingly for differing Inlet Temps.

[Theo]

I have an oil pressure gauge, and only take the occasional glance. No crashes yet!

I can't see how the MAF will sense charge temp, it measures air before it enters the turbo?

The engine has a knock sensor so I'd imagine that is how the engine stops itself from blowing up if intake temps are high enough to cause problems (det).

[GeoffBob]

Air temperature at the compressor outlet can be calculated with reasonable accuracy as a function of ambient air temperature (T_ambient), ambient barometric air pressure (P_1) and compressor pressure (P_2) according to the following equation:



where n_comp is the efficiency of the compressor (as a fraction between 0 and 1) at whatever point it is running on the compressor map at that point in time, and Gamma~1.4.

Keep in mind that the pressure is absolute (not relative) and temperature is in degrees Kelvin (not Celsius).

Take note that if we were to assume that the compressor were 100% efficient (n_comp=1) then this equation simply calculates the rise in temperature due to the adiabatic heating of the air as it is pumped through the compressor. Most of the heat, it has to be said, comes from pumping the air (adiabatic heating) and not as a result of compressor inefficiency.

Next we calculate the temperature of the air at the intake manifold (after the intercooler) according to:



where, in this case, n_ic is the efficiency of the intercooler (also a value between 0 and 1)

Assuming an ambient temperature of 27'C = 300'K and P2/P1=2.1, then the first equation determines a compressor outlet temperature of 394'K or 121'C. This assumes a typical compressor efficiency of around 75% for a GT25R.

Now, assuming an intercooler efficiency of 75% (based on your photo’s Theo) the second equation subsequently determines an intake temperature of 323.6'K or 50.6'C.

Theo, there is no doubt in my mind that (in your specific case) once you settle into a few laps (and your intercooler reaches thermal equilibrium) your intake temperature will be roughly 20'C higher than ambient. You could bring your intake air temperature down with a bigger cooler if you really wanted to, but personally I do not consider an intake temperature of 50’C to be particularly high, but then I am used to living in a hot climate where ambient air temperatures regularly climb to 35’C mid-summer.

Jon, with regards to your comment on water-air coolers - Take a close look at the second equation above. Water to air coolers are as close to 100% efficient as any cooler can get (n_ic~1) but in the case of a water-air cooler the "ambient" temperature is the temperature of the water you are pumping through the cooler. No matter how hard you try you will never cool your charge-air any cooler than the water you are pumping through the cooler. The above equation makes this quite clear. This is something you may need to consider in the case of your cooler. Don’t get me wrong, I am not suggesting that you are running engine water through your cooler (I assume that you have a separate coolant loop, at least I hope you do!) but unless you have adequate means to remove the heat from the water that the charge air is transferring into that water (via an adequate air cooled radiator) then your water is little else other than a ”aheat capacitor”a that will ultimately serve to warm, not cool, your charge air when off boost.

The same goes for an air-air cooler. You will never cool your charge any cooler than ambient air temp regardless of how efficient the cooler is. Apologies if I just stated the obvious, but some do fail to realise this.

HTH
Geoff

[Jon_Bmw]

Geoff, I like the equations, although the I don't know about the assumed values on the intercooler and turbo efficiency(I am not questioning you, I just don't know!).

Yes I understand the consequences of using a charge cooler on the car and it sharing the engine coolant. We were using fresh tap water and draining it straight out with a bit of resistance on the return line. Its nice when a car manufacture is paying the bill for a 120 hours running This is easily done in a dyno cell, slightly less easy on a car!

The problem we encountered(and thus the reason I would never reccomend a charge cooler) is that the fecking thing split!!! with rather obvious consequences. Unbelieveably we got away with it(it was on an idle stage and it seemed lumpy) and the engine survived the following 80 hours with a more conventional Air to Air intercooler. Interestingly, and not suprisingly, the charge cooler(with fresh cold'ish water) worked very well at reducing intake temps.

Your last paragraph sums up something obvious, which I failed to make more obvious, in my above post(s). The ambient temps Theo encountered were very high(for England!) that day, but some mega intercoolers can reduce the temps to <10'C over ambient. I'd still be concerned about 50, but perhaps thats just me. You'll certainly be loosing a small amount of power, on the plus side you can add that to the excuse book though, PHEW!

Theo, blonde moment reference the MAF.

[GeoffBob]

Geoff, I like the equations, although the I don't know about the assumed values on the intercooler and turbo efficiency(I am not questioning you, I just don't know!).

A ball-bearing turbo will give a maximum efficiency of around ~80%, a journal bearing typically no better than 75%. At P2/P1=2.1 the GT2560R will drop down to around 70% at 30lbs/min air-flow (about 300hp worth), so I simply assumed (thumb-sucked) an average value of 75%.

Likewise your typical e-bay air-air intercoolers are around 70 to 80% efficient. Not the best due to minimal turbulators inside the core. Sadly, there is usually so little cross-section to some of those cheap cores that if the manufacturer did actually bother to pack in some decent turbulators the pressure drop over the core (between inlet and outlet) would be ludicrous. And so, despite the fact that they offer minimal cooling capability, they do so without much of a pressure drop, which is better than having no intercooler at all .

The problem we encountered (and thus the reason I would never recommend a charge cooler) is that the fecking thing split!!! :

Sorry, I assumed you had issues with its cooling capability, and instead it turned out to be something a little more practical. At least you didn’t suffer hydraulic lock otherwise it would have been game over for that engine .

[crossie]

Quick thanks to Theo for the laps of the nurburgring - amazingly fast car and very well driven.

Cheers

[keri-WMS]

Theooooo, what's the latest...?

[Theo]

Car was mega as usual. Day was cut short slightly which is a great shame as I'd just set up the GoPro HD to film a couple of laps - gutted. I've got a video of Karan following me for part of a lap which I'll upload when I get a chance.

I think I'll fit a slightly longer diff next time I'm at the Ring as I was hitting the rev limiter halfway down the long strip and also at the hump at SX. I do have a lot of vibration from the front brakes now, pretty sure there's some deposits of pad material on the discs. Other than that the car is ready for more abuse!

Crossie, was good to catch up again. Glad you enjoyed the ride! We'll do it again next year. Or maybe later this year...

S

[keri-WMS]

Pad deposits are such a pain, there's a "scrubbing tool" I've seen that might help. In the states they use other pads to "scrub" the discs clean but it's a bit of a fine art.

I'm waiting for a new compound to be released to the public that to we could maybe try you on at some point...

EBC Orangestuff - full race only!

[Theo]

What's the scrubbing tool then? I was thinking of getting them very lightly skimmed.

I think these deposits have only come about because I swapped the pads around to try and combat the tapered pad wear. The actual performance of the PF01 pads is superb.

I am getting lots of small cracks on the surface of the front discs, perhaps I should use that nice brake ducting I've had lying around for the past few years? Or maybe some bigger front brakes....

[keri-WMS]

This thing - never used it but looks sensible! http://www.sears.com/shc/s/p_10153_1260 ... 2022474933



The small surface cracks are "normal" for a disc that's really pushed, as long as they don't all join up.



Have a search for "heat checking", it's amazing how far the process can go before failure:







Single long cracks are the real worry, and why I don't supply drilled discs if I can help it:

[Theo]

Cool, loving those gruesome pics!

My cracks are like your first pic, or a touch worse. I'll probably end up giving that silicon carbide brush a go and see if solves the problem.

[keri-WMS]

I saw a cracked train disc in the local machine shop a while back, got photos on my phone - very cool in a limits-of-engineering kind of way!

The honing thing should shift the pad deposits, cracking can't be helped much just keep an eye on it really.

[keri-WMS]

*...rummages in phone.....*

Ha-ha! Materials failure in a "large" brake disc (about 425-475mm x 30mm ish):

[Theo]

Having booked a track day at Rockingham at the end of the month I thought it would be a good idea to take my discs off and get them skimmed. Sadly they are in slightly worse order than I had thought..



Both of them are cracked in the same please, the one pictured is the worse of the two. Brembo Max discs - not a product I would recommend!

[keri-WMS]

Well I never, none of our grooved discs have ever done that as far as I know!

Plain old boring discs for the win I still think.

[Theo]

Luckily I have a spare pair of standard discs I bought from you, just need a very light skim after being in storage for a year or so.

I think we need to have a chat about your T30 caliper soon!

[keri-WMS]

[oldroydsr4]

Theo - PM sent about sr20.