Bobnova
02-25-2006, 11:30 PM
Hi, i just bought the SC bit off an SC.
To be specific, i bought the blower, and i'm trying to figure out a few things about it before i put it on my soon-to-be saab-engined Triumph TR7.
I searched around a decent bit, but haven't been able to find any specific answers, my apologies if i missed anything obvious.
1) Is there any easy way to tell whether i have a 2nd gen M90 or 3rd gen M90? The one i have does NOT have a bypass valve built in, and has "3.8" in red (with a red background? Blowers at my work right now) on the output bonnet.
2) Is the drive supposed to be a bit spongy? If i hold the rotor to prevent it's turning, and turn the pulley on the front it will turn a bit as if against a spring, then hit something and turn the rotor directly.
3a) What is the theoretical redline for blower speed?
3b) What is the theoretical maximum boost it can produce before getting dangerously hot? I've read about them overheating, having the rotors expand slight and touching, which kills everything. Output air temp going through the roof isn't what i'm worried about at this point in time, the TR7 has room for multiple HUGE intercoolers, it's the actuall blower overheating/overboosting i'm worried about.
Thats about it for questions, so i'll detail my plans briefly.
I have a '76 Triumph TR7, a small rwd british car with a huge engine bay, and an anemic two liter four banger.
I discovered that Saab 99(and 79-80 900) motors are nearly identical, and came in turbo form, with 7.2:1 compression and forged everything.
They can make upwards of 200hp in turbo form.
I figure that what 7.2:1 compression is really begging for is a blower, no more turbo lag, no more mushy throttle response!
The M90 is awefully big for a two liter engine, assuming perfect rotor sealing/VE a drive of 1:1 produces 4psi or boost, and 1.25:1 is 7-8psi.
In theory, i can run upwards of 36 pounds!
In reality of course it wouldn't put out 4psi at 1:1, as i doubt M90's are terribly efficient when being turned at engine speed (1k-6k redline).
Again, sorry if these questions have been answered somewhere and i just didn't search hard enough, i hate it when people show up on the other forums i'm on and ask questions before searching.
To be specific, i bought the blower, and i'm trying to figure out a few things about it before i put it on my soon-to-be saab-engined Triumph TR7.
I searched around a decent bit, but haven't been able to find any specific answers, my apologies if i missed anything obvious.
1) Is there any easy way to tell whether i have a 2nd gen M90 or 3rd gen M90? The one i have does NOT have a bypass valve built in, and has "3.8" in red (with a red background? Blowers at my work right now) on the output bonnet.
2) Is the drive supposed to be a bit spongy? If i hold the rotor to prevent it's turning, and turn the pulley on the front it will turn a bit as if against a spring, then hit something and turn the rotor directly.
3a) What is the theoretical redline for blower speed?
3b) What is the theoretical maximum boost it can produce before getting dangerously hot? I've read about them overheating, having the rotors expand slight and touching, which kills everything. Output air temp going through the roof isn't what i'm worried about at this point in time, the TR7 has room for multiple HUGE intercoolers, it's the actuall blower overheating/overboosting i'm worried about.
Thats about it for questions, so i'll detail my plans briefly.
I have a '76 Triumph TR7, a small rwd british car with a huge engine bay, and an anemic two liter four banger.
I discovered that Saab 99(and 79-80 900) motors are nearly identical, and came in turbo form, with 7.2:1 compression and forged everything.
They can make upwards of 200hp in turbo form.
I figure that what 7.2:1 compression is really begging for is a blower, no more turbo lag, no more mushy throttle response!
The M90 is awefully big for a two liter engine, assuming perfect rotor sealing/VE a drive of 1:1 produces 4psi or boost, and 1.25:1 is 7-8psi.
In theory, i can run upwards of 36 pounds!
In reality of course it wouldn't put out 4psi at 1:1, as i doubt M90's are terribly efficient when being turned at engine speed (1k-6k redline).
Again, sorry if these questions have been answered somewhere and i just didn't search hard enough, i hate it when people show up on the other forums i'm on and ask questions before searching.