1983 BMW E24 635csi Track Car Turbo Build

1983 BMW E24 635csi Track Car Turbo Build

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e28525e

Original Poster:

462 posts

142 months

Sunday 10th September 2023
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rallycross said:
e23 745i - wow that’s a rare beast a pals dad had one doubt you’d ever find one now - good idea to use stock spec cams will be well designed for use with the boost…
Yeah, shame we never got them over here! Or the M88 variant..

Mark-Clio182Trophy

16,205 posts

174 months

Sunday 10th September 2023
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e28525e said:
Hello, all

Another little update. I've found some Siemens 875cc injectors for a decent price so these will be getting ordered in time for the next tuning session on November 1st. Boost will be turned up to approximately 1.2 bar (currently 0.8).

I have also ordered a new AFR sensor as the one fitted had done it's time and the oil temp gauge has also given up so I have another one of those to fit as well. I am currently using the oil pressure to figure out when everything is up to temp!

Installing an aftermarket M30 "turbo" cam or hotter Schrick was also considered but these tend to alter the torque delivery and you lose the early shove you get from the stock B35 cam. This stock camshaft was used in the e23 745i and the Alpina B10 Bi-Turbo, so you'd think it would be a decent compromise!

Vernier pulley was also considered but as the cam operates both the inlet and exhaust valves, playing with this would simply move the power band up or down the rev range and, as you set it and then button it all up and see what happens, it's a bit of a risk when you're paying for a full tuning session without the ability to alter timing..

A new exhaust will be made up for the run, the single side exit box has had a kicking and it's now too loud to pass track limits and also is very uncomfortable in my right ear! Going back to a 4" with rear exit and two silencer boxes is the order of the day.

Here is some footage of the power run:

https://www.youtube.com/watch?v=vy2nWTfQTPA&li...

Cheers!
Fantastic!

shalmaneser

5,936 posts

196 months

Monday 11th September 2023
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Such a cool car and must get a move on with ~400bhp!

e28525e

Original Poster:

462 posts

142 months

Monday 11th September 2023
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shalmaneser said:
Such a cool car and must get a move on with ~400bhp!
It goes pretty well, yeah! To be honest, it's more about the torque, 400lbft feels pretty peppy in a car that weighs the same as a Polo GTI biggrin

Dr.Hellno

112 posts

16 months

Monday 11th September 2023
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Like any other normal human with eyes, I love a 635csi.

Awesome build, man!

Sf_Manta

2,195 posts

192 months

Tuesday 12th September 2023
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Loving this, and how neatly executed with the engine bay. Very nicely done man.

e28525e

Original Poster:

462 posts

142 months

Tuesday 19th September 2023
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Fanks


e28525e

Original Poster:

462 posts

142 months

Wednesday 18th October 2023
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Another update.

Two more days spent on the Turboshark. Firstly, we dropped the diff and fuel tank. Steve set about swapping the 3.73 crown and pinion for a 3.23, this will make the most of the torque and allow a 160mph+ top speed. Meanwhile I cut a hole in the tank in order to install a universal VDO level sender. The old one fell to bits and the space is now occupied by the Walbro 255 lift pump.

Diff back together with new oil:



Fuel tank dropped and new sender installed. This tank is date stamped 2001 and is in great shape. However, there isn't any protection from road poo and there was already a sizeable amount of mud stuck to the top which you'd never be able to clean off when on the car. I cleaned it up and coated it with stonechip.



While both of these were off the car, it made sense to reinforce the boot floor/diff mount as it'll be handling well over double the torque it was ever supposed to. The swirl pot and filter had to be removed in order to do this and these will have to be slightly modified in the way they mount in order to accommodate the reinforcement.







Lastly, it made sense to also reinforce the rear ARB mounts. The steel used for these is thinner than that used for the brackets that hold the old fuel filter and pump assembly!







Weather is turning inclement so a gazebo has been ordered. I've spaffed a lot of money on some 4" piping and a couple of silencers for the new exhaust. This will be be the main focus next week, along with installing an accusump system.

Cheers!

Edited by e28525e on Wednesday 18th October 22:28


Edited by e28525e on Wednesday 18th October 22:44

e28525e

Original Poster:

462 posts

142 months

Thursday 19th October 2023
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Anorak post. Gear speed changes for the 3.73 vs the 3.23 which has just been installed. Full boost is at 2750rpm.

3.73
............1...........2.............3.............4..............5
6500 33.48.....58.16.....91.53.....127.95.....157.39
6000 30.90.....53.69.....84.49.....118.11.....145.28
5500 28.33.....49.21.....77.45.....108.27.....133.17
5000 25.75.....44.74.....70.41.....98.43.....121.07
4500 23.18.....40.27.....63.36.....88.58.....108.96
4000 20.60.....35.79.....56.32.....78.74..... 96.85
3500 18.03.....31.32.....49.28.....68.90..... 84.75
3000 15.45.....26.84.....42.24.....59.06..... 72.64
2500 12.88.....22.37.....35.20.....49.21..... 60.53
2000 10.30.....17.90.....28.16.....39.37..... 48.43
1500 7.73 .....13.42.....21.12.....29.53..... 36.32
1000 5.15 ..... 8.95 .....14.08.....19.69..... 24.21

3.23
............1...........2..............3..............4..............5
6500 38.66.....67.16.....105.70.....147.76.....181.75
6000 35.69.....62.00.....97.56 .....136.40.....167.77
5500 32.71.....56.83.....89.43 .....125.03.....153.79
5000 29.74.....51.66.....81.30.....113.66 .....39.81
4500 26.77.....46.50.....73.17.....102.30.....125.83
4000 23.79.....41.33.....65.04..... 90.93 .....111.85
3500 20.82.....36.17.....56.91..... 79.56 ..... 97.86
3000 17.84.....31.00 .....48.78..... 68.20..... 83.88
2500 14.87.....25.83 .....40.65..... 56.83 ..... 69.90
2000 11.90.....20.67......32.52..... 45.47 ..... 55.92
1500 8.92.....15.50 .....24.39..... 34.10 ..... 41.94
1000 5.95.....10.33......16.26 ..... 22.73..... 27.96

JJJ.

1,378 posts

16 months

Thursday 19th October 2023
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The new max speeds in 2nd and particularly 3rd gear really appeals.

Mark-insert old BMW

16,205 posts

174 months

Thursday 19th October 2023
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Wasn't there a 3.07 ?

Dinoboy

2,510 posts

218 months

Friday 20th October 2023
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JJJ. said:
The new max speeds in 2nd and particularly 3rd gear really appeals.
Yeh, under 50mph all the way to nearly 110mph in 3rd is fab.

e28525e

Original Poster:

462 posts

142 months

Friday 20th October 2023
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Mark-insert old BMW said:
Wasn't there a 3.07 ?
There was, yes. It's what the car originally had from factory. It is just too long to be useful though -top speed would be 190.8mph!

It would mean having to grab 2nd gear on some tracks and that would be pointless as it would be peak torque at that point. Trying to deploy 500lb ft at 40mph with lock on would mean many additions to my black flag tally biggrin

Edited by e28525e on Friday 20th October 09:01

Mark-insert old BMW

16,205 posts

174 months

Saturday 21st October 2023
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e28525e said:
top speed would be 190.8mph!
Imagine that. laugh

e28525e

Original Poster:

462 posts

142 months

Saturday 21st October 2023
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Mark-insert old BMW said:
Imagine that. laugh
Haha! I think I'd need to do some aero work to stop it trying to take flight. I know the B7S had a top speed of 165mph so I use that as the theoretical maximum this body was tested to...

e28525e

Original Poster:

462 posts

142 months

Friday 27th October 2023
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Steve made the exhaust over the past couple of days. 3 and 2 inch dumps into 4 inch.








Accusump mounted and plumbed in


e28525e

Original Poster:

462 posts

142 months

Friday 17th November 2023
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Unfortunately, the most recent tuning session revealed a fuel pressure issue. This means I'm using it as an excuse to update the fuel system. The single 023 (044) pump and swirl pot is being removed and in it's place will be a twin Syvecs pump and surge tank setup. A new rail is being made up from extruded aluminium as the Nuke one never fitted properly (it hit the stat housing) and twin top hat extenders had to be used. Lastly a new FPR is going in with new pipework.

I am hoping to get this all in and tuned before the trackday I have booked on the 9th of December. It's looking unlikely that the old girl will make it so I may be taking the E30 again, which is no bad thing! Anyway, fingers crossed...

braddo

10,611 posts

189 months

Friday 17th November 2023
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Loving the work on this!

e28525e

Original Poster:

462 posts

142 months

Friday 22nd December 2023
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A small update -

New surge tank and twin pump setup in place, just wiring to finish.



New fuel rail has been drilled and fitted, just need some fittings and spacers for the mounting points.



I've booked in to finish the mapping session on the 29th of January.


e28525e

Original Poster:

462 posts

142 months

Tuesday 30th January
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The mapping session went well! I think we ran into a restriction on the inlet side, as only intake temps were increasing after a point, with little climb in peak hp or torque. Either way, the car is very driveable now. The only issue we ran into was a leaking oil feed on the turbo. I am going to try some "Hot-Lock" extreme temp threadlock, as it's an issue I've had with at least two combos of fittings.

Here is the graph. As you can see, very useable power.



As a comparison, I have seen turbo M30's making 150 more PEAK horsepower with as much as 60bhp and 80ftlb less at 3k rpm, when compared to this setup.

I feel the car should be making around 15% more power at this boost level, so I may try a different intercooler at some point.

I am hoping to insulate the pumps from the body of the car asap as they are ridiculously loud, as in, louder than the engine or exhaust at full chat.

The car is now around 325bhp/tonne and 345lbft torque/per tonne. Equivalent to a Jag XJ220/Noble M12 GTO 3R for power - Ferrari Monza SP2 V12 Aventador LP770-4 SV for torque.



The next jobs will probably be to extend the cage and possibly fit larger brakes.

Cheers!