2.7 turbo advice needed
Moderator: martauto
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daveo
- E30 Zone Newbie
- Posts: 60
- Joined: Sun Dec 11, 2005 11:00 pm
- Location: Chester ,Cheshire
im buliding a 2.7 m20 engine from a 525e and i was thinking about puting a turbo on it would this spec be ok to run a turbo rebuilt 525e bottom end 325 low comp pistion with the bolck skimmed 325 head 272 cam.
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Ant
- Retired Team Member
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Cr will be quite high dude, about 10:1 depending on how much you take off the deck height.
272 cam will have too much overlap/duration for turbo, the intake charge will be blown out of the ex valves on the overlap.
you need to decide, N/A or FI and build accordingly, the two are incompatable spec wise.
build it 8:1 and turbo, or go the N/A route, the decision is yours
HTH
272 cam will have too much overlap/duration for turbo, the intake charge will be blown out of the ex valves on the overlap.
you need to decide, N/A or FI and build accordingly, the two are incompatable spec wise.
build it 8:1 and turbo, or go the N/A route, the decision is yours
HTH
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Email FTW-
e30_Turbo
- Boost Junkie
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What he said! 
Morning Ant
Morning Ant
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daveo
- E30 Zone Newbie
- Posts: 60
- Joined: Sun Dec 11, 2005 11:00 pm
- Location: Chester ,Cheshire
i think il take the n\a route. thanks for help
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Gunni
- E30 Zone Addict
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go both ways,
Do a high end setup, i.e run a 272cam + a turbo that comes in late.
more specifically make sure that after you change gears your still in the powerband,
The bottom end will see minor boost (could be 10psi at 3500rpm) but when the turbo reaches max
boost say 4200rpm (maybe 1bar) you should be able to carry that efficiently to the redline at the turbines and compressors max efficiency rather then push against the cam and on a smaller turbo.
1bar at 6k isn´t just 1bar at 6k, if the turbine isn´t expelling the pressure from the exhaust manifold the hot air can go back into the engine(of course not everything) as there is more pressure on the exhaust side then intake, the gains go even bigger with a stronger cam as more is getting into the engine, again you need a bigger turbo to relieve the pressure making the gains again more.
Ant :
Have you had blow through happen with a wild cam, and if so how did you measure it?
Do a high end setup, i.e run a 272cam + a turbo that comes in late.
more specifically make sure that after you change gears your still in the powerband,
The bottom end will see minor boost (could be 10psi at 3500rpm) but when the turbo reaches max
boost say 4200rpm (maybe 1bar) you should be able to carry that efficiently to the redline at the turbines and compressors max efficiency rather then push against the cam and on a smaller turbo.
1bar at 6k isn´t just 1bar at 6k, if the turbine isn´t expelling the pressure from the exhaust manifold the hot air can go back into the engine(of course not everything) as there is more pressure on the exhaust side then intake, the gains go even bigger with a stronger cam as more is getting into the engine, again you need a bigger turbo to relieve the pressure making the gains again more.
Ant :
Have you had blow through happen with a wild cam, and if so how did you measure it?