Turbo my E34.... twins work

[NAT9566]

I can picture a new Halfcut engine M20-B25 12valver with twin turbos, a small one and a big one..... with standard AFR and engine management....
Free flow cone air intake
Turbos can be from skyline and volvo 940 turbo, intercooler from Pajero... :lol:
ALso how much torque could i get..
Power is a separate issue... i know it would hit 240 bhp..... (without stressing the engine of course.. (1.1 bar boost is more than enough XD XD)

PS.. if i can get an Eta engine... i'd be happy too... bolt on the 2.5 head and voila.. perfect turbo engine

[BigKriss]

do you want the turbo's running in parallel or sequence? becasue I don't understand why you say you want two turbos, a small one and a big one?

[Omega]

Must be sequence. Small one to spool up quick and give some pressure to the huge one which will come on song higher in the rev range. This system worked very well on Lotus Carltons in the early 90's.

Do you think it is worth the effort for 240 bhp? The standard UK spec m50 24v is rated at 190bhp adding a 100hp shot of nitrous would get you about 240-250bhp for much, much less effort.

JonK is the forced induction guru so I shall await his opinion....

[NAT9566]

yes, sequential turbos are wanted ... and i mentioned i am planning to use the more robust and userfriendly m20.... eta blocks are hard to find so the best choice i have is a b25 from a rear ended car from the breakers yard ( blasted lorry !) (however the current economic situation is not good for my venture)
since my car is currently using a m20 block, putting another would require less wiring work, also the valve stems are robust... m50's are still too expensive to service... even on my i
own...
Ps.... The turbo's are more for the torque... With the power at 170 bhp... a 70hp addition is substantial ... torque is still needed....
Also, I am now in the SEA.... Malaysia to be exact.... my company sent me, and the expat lifestyle is not all that great...
sourced a very expensive e34 (RM20k = 2.8k sterling) which has the same specs as mine..... (blasted co. ... they did not give me a good car....)
So planning to do the conversion when i return in winter...

[winfred]

a goal of 240 is not worth the effort of compound turbos, 240 can easyly be made with a single with a nice fast spool up, i am planning on making more then 240 with my blower/stroker m20 project, maybe 400 hp or more and twins would be worth the plumbing nightmare, not sure id bother with compound twins unless you were planning foolish amounts of boost, paralel twins would be easyer, diesel guys run compound twins to get above 50 psi without long spool up times and usually are running them in the 70 psi range with a few pushing 100

[Jon K]

Lots of misinformation in that first post. Firstly, NAT9566, if you are going to sequential turbo a car, there's a lot more math involved than "Turbo from this, turbo from that." You have an M20 12v. Twin turbo makes each a function of a 1.25 Liter 6 valve. With that little displacement and that little flow, it seems counterproductive to try and match two unequal sized turbos to the system. 1.1 bar of boost is more like a 350 horsepower setup. But, boost is not a proponent of horsepower - I can run a tiny turbo at 30 psi and make less horsepower than my turbo at 12 psi.

There is no point in twin turboing your car. You will not want to know what kind of plumbing is involved. Twin oil feeds, twin oil drains (as if one isn't troublesome enough), twin down pipes, twin inlets, twin air filters, etc. And, because you seem to want to run compound turbo sizes, you will be dealing with reversion - you can't simply have two turbos blowing into the same pipe because the one making higher boost will actually stall and blow back through the intake of the one not yet turning fast.

On gasoline engines, cars make way more horsepower and torque on single larger turbos than twins. Take Toyota Supra as my favorite example - stock twin turbo are 99% always removed for a single large unit. Granted they induce lag with the large turbos, but something like a GT35R spools like nothing.

As for the management, "with standard AFR and engine management....
Free flow cone air intake" really not sure you fully understand or maybe its a language barrier, but AFR has nothing to do with this. Standard engine management? Bro even I would have a hard time designing a plumbing/sensor setup for that kind of whacked out turbo build, let alone anything "standard".

If you really do intend to do something like this you must sit down and think it through logically - I've had a ton of friends start things like this and then just stop - total waste.

[NAT9566]

I am sorry if i came across as being ambiguous, the truth is, i want more torque ( leading to a better fuel economy) so i figured sequential turbos would give me some power in a cheap form..(in the long run)
It looks that i may have been misinformed and would probably be better off with a stroker kit on a m20b25 block.

So my options are as follows
1. parallel small turbos on a m20b25
2.single midsize turbo on a m20b25
3. parallel small turbos on a m20b27 with a b25 head
4.single midsize turbo on a m20b27 with a b25 head
5. parallel small turbos on a m30b30
6. single midsize turbo on a m30b30

Also..... My minimum torque requirement is around 230Nm at 2500rpm....
(please advise if it be unreasonable....)
THank you all for the criticism and the like

PS>... also i prefer a car that remains drivable... and a 6spd gbox is too expensive....

[winfred]

#2 and #4 would be the best/cheapest choices, your torque figure of 230nm/170 foot pounds is close to the stock rating of a b27, one of the better motors to start with is the 88 super eta it's a 2.7 that already has the I b25 head on it, so it has the correct pistons for the I head (E pistons won't work unless you want to push lots of boost to make up for the really low compression) but the cam in the super E is not the regular I cam and it only has single valve springs, a super E motor with a I cam/springs (or maybe a aftermarket performance cam) and I injection computer with a few bolt on goodies like a chip and some headers may be the motor you want for the stated power level without going to a turbo

I am sorry if i came across as being ambiguous, the truth is, i want more torque ( leading to a better fuel economy) so i figured sequential turbos would give me some power in a cheap form..(in the long run)
It looks that i may have been misinformed and would probably be better off with a stroker kit on a m20b25 block.

So my options are as follows
1. parallel small turbos on a m20b25
2.single midsize turbo on a m20b25
3. parallel small turbos on a m20b27 with a b25 head
4.single midsize turbo on a m20b27 with a b25 head
5. parallel small turbos on a m30b30
6. single midsize turbo on a m30b30

Also..... My minimum torque requirement is around 230Nm at 2500rpm....
(please advise if it be unreasonable....)
THank you all for the criticism and the like

PS>... also i prefer a car that remains drivable... and a 6spd gbox is too expensive....

[Jon K]

#2 and #4 would be the best/cheapest choices, your torque figure of 230nm/170 foot pounds is close to the stock rating of a b27, one of the better motors to start with is the 88 super eta it's a 2.7 that already has the I b25 head on it, so it has the correct pistons for the I head (E pistons won't work unless you want to push lots of boost to make up for the really low compression) but the cam in the super E is not the regular I cam and it only has single valve springs, a super E motor with a I cam/springs (or maybe a aftermarket performance cam) and I injection computer with a few bolt on goodies like a chip and some headers may be the motor you want for the stated power level without going to a turbo

I agree - there is no point in attempting to run even a single turbo with such low requirements.

PS winfred I have boost control working with MS So sick.

[winfred]

cool, i haven't had time to screw with mine since i got it built but i gotta get on it soon as i am probably going to finish my motor today, whats your favorite active idle control, i've done the tip120 pwm stuff but on further reading i am not sure if this is the right way for real idle control, everybody seems to have their own way of running a 3 wire bosch valve

PS winfred I have boost control working with MS So sick.