SFR supercharger
03-07-2012, 09:06 PM
#31
Burning Brakes
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. You can find running 951 motors all day for under a grand. A bare 968 block will get you at least $700 and you can probably get close to that for the crank as well. Most of the equation here is due to availability and the other part to turbo guys who wanted to build 3l motors(prior to the word getting out about MID sleeving). As far as what motor is more desirable, the 968 motor has a ton of R&D in it. I forget where I read the article about all the changes made from the s2 to the 968 motor, but it was a great read. It is the better motor from the factory. The 951 motor has more potential with simple bolt-on modifications.
03-08-2012, 03:12 AM
#32
Rennlist Member
Yes, I think I already made the point that supercharging a 968 engine with any kit pretty much equals tinkering and reduced reliability. Same goes for any engine swap.
If you want stock like reliability, stay stock. If you want a bit more power with a stock 968 engine, a set of headers, cams and a bit of tuning can wake up a stock NA 968 nicely, without the inevitable project work that comes from getting forced induction to run, turbo or supercharger.
If you want stock like reliability, stay stock. If you want a bit more power with a stock 968 engine, a set of headers, cams and a bit of tuning can wake up a stock NA 968 nicely, without the inevitable project work that comes from getting forced induction to run, turbo or supercharger.
03-08-2012, 10:30 AM
#34
Team Owner
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i must respectfully disagree.
there is not 1 part of the LSx puzzle that has not been solved to near normal GM reliability.
and GM LSx reliability is very good.
oil pan/crossmember - solved.
motor mount reliability - solved.
serpentine/engine compartment spacing - solved.
cooling - solved.
cooling fan operation - solved.
oil cooling - solved.
ac - solved.
ps - solved.
full power braking - solved.
anti-lock braking - no issues.
intake/throttle body clearance - solved.
front A-arms spacing - solved.
bellhousing adaptor spacing/fitment - solved.
clutch issues - solved.
low-quality oem driveshaft - solved.
short gears/final drive ratio - solved.
reduced cv joint life - solved.
all dash instrumentation - solved.
compare to Porsche/oem. the Porsche 944 engine is decent... the semi-exotic nature of the maintenance schedule/cost vs performance, is extremely difficult to justify... 944 engine support components falls somewhere between poor~extremely poor....... the 968 engine is superb... the semi-exotic nature of the maintenance schedule/cost vs performance is pricey. engine support components/reliabilty; fair.
03-08-2012, 10:37 AM
#35
Rennlist Member
You miss my point. I love the V8 swap. I can see it has been well thought out for this car. I love engine swaps in general and have done several on various cars. I am seriously looking at it for my car if the classes of racing suit in Australia.
What I think though, is that any person who doesn't like tinkering, is worried about getting involved in R&D or having to figure out non standard solutions and is worried about stock reliability as priorities is probably not the best candidate to be doing any type of engine swap, supercharger kit install or turbo modification. I doubt they will enjoy the process much, that's all.
The problem I see with supercharger kits in general is the impression given that it is just a bolt on solution, like bolting on a set of headers. It just isn't that simple in most cases.
What I think though, is that any person who doesn't like tinkering, is worried about getting involved in R&D or having to figure out non standard solutions and is worried about stock reliability as priorities is probably not the best candidate to be doing any type of engine swap, supercharger kit install or turbo modification. I doubt they will enjoy the process much, that's all.
The problem I see with supercharger kits in general is the impression given that it is just a bolt on solution, like bolting on a set of headers. It just isn't that simple in most cases.
Last edited by Dubai944; 03-08-2012 at 10:58 AM.
03-08-2012, 12:06 PM
#36
Addict
Rennlist Member
Rennlist Member
As far as the 968 internals, the early rods are suspect at stock power levels. The later rods seem pretty good. Search on 1r and 2r rods and you will read about this issue.
The short piston skirts IMO are not great for boost. The may be less of an issue in the 968 with the oil squirters than it is in the S2. Bore scuffing is a worry due to a lack of good skirt support.
Whatever is done, RPMs and knock need to be kept in check, particularly under boost. Tip-in detonation is also a concern I have and I am working on a way to slow the boost hit as I think on a hot day this can be a very dangerous condition. The problem there is that at cruise with light throttle the supercharger is ready to deliver boost but the ECU is in economy cruise mode with lots of timing dialed in. Unlike a turbo, boost does not build slowly but hits once the throttle plate opens and the recirculation valve closes. The ECU might get the WOT signal but not before the boost comes roaring in and meets all that timing. Particularly bad news on a hot day.
-Joel.
The short piston skirts IMO are not great for boost. The may be less of an issue in the 968 with the oil squirters than it is in the S2. Bore scuffing is a worry due to a lack of good skirt support.
Whatever is done, RPMs and knock need to be kept in check, particularly under boost. Tip-in detonation is also a concern I have and I am working on a way to slow the boost hit as I think on a hot day this can be a very dangerous condition. The problem there is that at cruise with light throttle the supercharger is ready to deliver boost but the ECU is in economy cruise mode with lots of timing dialed in. Unlike a turbo, boost does not build slowly but hits once the throttle plate opens and the recirculation valve closes. The ECU might get the WOT signal but not before the boost comes roaring in and meets all that timing. Particularly bad news on a hot day.
-Joel.
03-08-2012, 05:16 PM
#37
Three Wheelin'
As far as the 968 internals, the early rods are suspect at stock power levels. The later rods seem pretty good. Search on 1r and 2r rods and you will read about this issue.
The short piston skirts IMO are not great for boost. The may be less of an issue in the 968 with the oil squirters than it is in the S2. Bore scuffing is a worry due to a lack of good skirt support.
Whatever is done, RPMs and knock need to be kept in check, particularly under boost. Tip-in detonation is also a concern I have and I am working on a way to slow the boost hit as I think on a hot day this can be a very dangerous condition. The problem there is that at cruise with light throttle the supercharger is ready to deliver boost but the ECU is in economy cruise mode with lots of timing dialed in. Unlike a turbo, boost does not build slowly but hits once the throttle plate opens and the recirculation valve closes. The ECU might get the WOT signal but not before the boost comes roaring in and meets all that timing. Particularly bad news on a hot day.
-Joel.
The short piston skirts IMO are not great for boost. The may be less of an issue in the 968 with the oil squirters than it is in the S2. Bore scuffing is a worry due to a lack of good skirt support.
Whatever is done, RPMs and knock need to be kept in check, particularly under boost. Tip-in detonation is also a concern I have and I am working on a way to slow the boost hit as I think on a hot day this can be a very dangerous condition. The problem there is that at cruise with light throttle the supercharger is ready to deliver boost but the ECU is in economy cruise mode with lots of timing dialed in. Unlike a turbo, boost does not build slowly but hits once the throttle plate opens and the recirculation valve closes. The ECU might get the WOT signal but not before the boost comes roaring in and meets all that timing. Particularly bad news on a hot day.
-Joel.
To help with this I run the open loop PT on the track. This lets me run richer than 14.7:1 in PT before transitioning to WOT fuel. In effect in PT I have around 12.5:1 in the higher load/rpm areas of the map. I have also retarded the WOT ignition as well as retarded the high RPM and high load cells in the PT ignition maps.
03-09-2012, 02:01 AM
#39
Three Wheelin'
Yep - and I was under no illusions that it would be straightforward (especially since I built up my installation from scratch). BUT, I actually found the tuning easier than expected.
03-09-2012, 04:13 AM
#40
Racer
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What I think though, is that any person who doesn't like tinkering, is worried about getting involved in R&D or having to figure out non standard solutions and is worried about stock reliability as priorities is probably not the best candidate to be doing any type of engine swap, supercharger kit install or turbo modification. I doubt they will enjoy the process much, that's all.
Perhaps we both overstate our case.
The 968 motor didn't get by itself into my 944NA. However, not much tinkering was necessary to install; once installed, no tinkering since and behaves and feels like stock. (Well, O.K., because in a way it is stock!). Especially the jump in torque must have added a lot stress to the drivetrain, but after 10 years and 50 000 miles plus no problems.
I see no reason why a well sorted, low-boost supercharger kit - IF used within the design parameters - should be much different or must be an ongoing R&D project.
Of course, once moving into high-boost it becomes a completely different story moving out the realm of just installing a kit adding a supercharger. My understanding is to do it right requires rebuilding the engine for boost (low compression and suitable head gasket), redo the belt drive system, and in-depth reconsideration of engine management.
MN
Last edited by MN; 03-09-2012 at 05:19 AM.
03-09-2012, 11:21 AM
#41
Rennlist Member
03-11-2012, 07:13 PM
#44
Racer
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True, but the "well sorted" part will be the job you have to do yourself.
Wished that more supercharger users would chip in.
MN
