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2.5 Monster Motor
Posted: Fri Jul 20, 2012 9:08 am
by Crazyswede
Not sure where the original conversation went but here is a new one to chronicle peoples progress on building this monster, the parts used, and the procedure.
Parts:
T7 Head
2.1 Block
early 2.3 crank (93 and earlier)
Custom pistons (debate on whether stock can be used)
New Rods (debate on whether stock can be used)
Modded timing covers
Modded intake.
T5 fuel injection
Re: 2.5 Monster Motor
Posted: Fri Jul 20, 2012 9:18 am
by SwedeSport
Has anyone tried it with a turbo, or are they all NA builds?
I have a pair of 2.1 blocks....
Re: 2.5 Monster Motor
Posted: Fri Jul 20, 2012 10:25 am
by Crazyswede
SwedeSport wrote:Has anyone tried it with a turbo, or are they all NA builds?
I have a pair of 2.1 blocks....
I think there was someone in sweden running a 2.5 8v turbo in Sweden in a rally car. They were running it as an 8v due to class structures. It will work as an 16v turbo but the general consensus is that you won't be able to build a strong enough transmission unless you can get one of the big turbo rally boxes.
Re: 2.5 Monster Motor
Posted: Fri Jul 20, 2012 10:44 am
by Luke
Crazyswede wrote:Not sure where the original conversation went but here is a new one to chronicle peoples progress on building this monster, the parts used, and the procedure.
Parts:
T7 Head
2.1 Block
early 2.3 crank (93 and earlier)
Custom pistons (debate on whether stock can be used)
New Rods (debate on whether stock can be used)
Modded timing covers
Modded intake.
T5 fuel injection
To be done right it will need aftermarket rods and pistons for sure. The stock 2.3 rods are way too long even with the shortest stock piston in the B212, not to mention way too heavy. Also the big ends are way too big to clear both the engine casting and the transmission.
That said, we need as long and light of a rod as we can get with a very short custom piston. The oil scraper will have to bisect the wrist pin. The rods need to be as as long and light as possible to keep the angle at which the rod must swing through reduced, which minimizes the natural 2nd order imbalance in a 4cyl engine. The formula is to use a chevy small block aftermarket superlight rod with low very low profile big ends. They are cheap, $500-600 for a set of 8. The crank needs to be ground to use the chevy rod bearing which is slightly smaller than the stock SAAB and this keeps the and keeps the big end dimensions smaller and thus with the block clearance issue. The Swedes were making 200HP with this combo with a big valve 8V head, a T7 head with proper cams should be a nice amount more :)
I'm really considering this, but if I do it I will do it right.
Heres a rough breakdown of estimated costs.
Rods $300
Pistons $650
Crank Grinding and Nitritiding Crank: $350
Enem or Catcams Cams: $800
stiffer valve springs: $200
ITB throttle bodies: $650
So assuming we already had blocks/cranks/heads we could built a pretty god damn awesome motor for ~3K.
Re: 2.5 Monster Motor
Posted: Fri Jul 20, 2012 11:01 am
by DrewP
I'm getting antsy just waiting to see what a stock 2.0 bottom end with a T7 head and a good T5 tune and headers is going to make.
I'm thinking that combo in the stripped out road race car should still be pretty freakin fast.
The engine that Dave Kennedy built for one of my customers with Wiseco pistons used some off the shelf small block rods for a Ford, maybe a 327, I don't recall.
Re: 2.5 Monster Motor
Posted: Fri Jul 20, 2012 1:33 pm
by Crazyswede
DrewP wrote:I'm getting antsy just waiting to see what a stock 2.0 bottom end with a T7 head and a good T5 tune and headers is going to make.
I'm thinking that combo in the stripped out road race car should still be pretty freakin fast.
The engine that Dave Kennedy built for one of my customers with Wiseco pistons used some off the shelf small block rods for a Ford, maybe a 327, I don't recall.
How does the volume in the T7 combustion chamber compare to a 2.1/2.3 head and to the 2.0 head? I know that 2.1/2.3 heads are a bit bigger and lower the compression on a 900 motor.
Re: 2.5 Monster Motor
Posted: Fri Jul 20, 2012 1:52 pm
by DrewP
Good point, they're definitely larger, but I haven't gotten around to CC-ing mine yet.
The T7 pistons have either basically flat tops, or very shallow dishes depending on whether it's in a 2.0 or 2.3.
Re: 2.5 Monster Motor
Posted: Fri Jul 20, 2012 1:55 pm
by Luke
As I recall the they are actually less CC than a 2.1/2.3 head. I CC'd a T5 but I cant find my notes for that. The T7 combustion chamber looks identical to t5 but will be a bit less because the valves are dished. But the T7 headgasket is also a lot thinner....
Re: 2.5 Monster Motor
Posted: Fri Jul 20, 2012 2:18 pm
by Rallyho
My (un)calibrated butt-dyno tells me that a 2.0 bottom end, 2.1 head, header and mostly tuned T5 makes good torque and doesn't seem to mind reving up to a self-imposed rev limit of 7200. Car currently has some cams in it...not sure what the grind is. Jordan and Kip might be able to answer.
Some thoughts on the monster motor.
There may be an off the shelf performance piston that will work with light mods. There are a lot of Chevy and Ford parts out there.
A 2.0 block with the 2.3 crank might get you 95% of what your going to get with the 2.1 block. And interweb lore has it that the 2.0 blocks are stronger.
T5 FTW. I'm pretty certain that with some tuning time, on a dyno, T5 will wring out every available pony and let you dial into a super reliable motor that give consistent power.
For an NA motor, the S&R gearbox makes it... gears, diff, R&P. That puts the power where you can use it in a rally car.
Re: 2.5 Monster Motor
Posted: Fri Jul 20, 2012 2:30 pm
by Hans
Luke wrote:As I recall the they are actually less CC than a 2.1/2.3 head. I CC'd a T5 but I cant find my notes for that. The T7 combustion chamber looks identical to t5 but will be a bit less because the valves are dished. But the T7 headgasket is also a lot thinner....
Luke, in an old PM to me re: b2x4 chamber volume wrote:I did get a chance to CC it last time I had it apart. I got 45 cc's. I got 48 cc's for a 2.1 btw.
Re: 2.5 Monster Motor
Posted: Fri Jul 20, 2012 2:42 pm
by Luke
Hans wrote:Luke wrote:As I recall the they are actually less CC than a 2.1/2.3 head. I CC'd a T5 but I cant find my notes for that. The T7 combustion chamber looks identical to t5 but will be a bit less because the valves are dished. But the T7 headgasket is also a lot thinner....
Luke, in an old PM to me re: b2x4 chamber volume wrote:I did get a chance to CC it last time I had it apart. I got 45 cc's. I got 48 cc's for a 2.1 btw.
Ha there ya go, thanks Hans for being way more organized than me!
Re: 2.5 Monster Motor
Posted: Fri Jul 20, 2012 8:18 pm
by Jordan
The .040" skimmed 2.1/3 head that is on Mike's I cc'd at 45 or 42....now I forget, but I do have it written down somewhere...
I didn't have the cc of N/A 2L pistons.. but I roughly estimated a 10.5:1 compression ratio thinking they would probably add only a couple of ccs to the total volume.
I know Kip is on board, maybe for this fall... I have two 2.1 blocks, 1 crank, and of course all the T5 stuff. The ITBs and cams can be added later IMO.
I know you can roughly figure potential HP based on the head flow numbers... I have access to a flow bench as well and can take stuff over and play around for a day.
Re: 2.5 Monster Motor
Posted: Fri Jul 20, 2012 9:37 pm
by Darth Blomqvist
I have two more cranks on the way and at least one or two 2.1 blocks kicking around. My next store neighbors where I work build drag motors, and it turns out the father of the father and son team used to run saab and DKW two strokes back in the day. I just gave him a trans for his 91’ 900 convert and talked to him about the stroker motor. He is on board as far as helping with the Merican’ rotating parts.
It looks like John Groo has the connection to turn down the cranks. The custom pistons will have to be figured out via piston height, pin height ect. This is the part that might vary upon individual’s choice of what head to use, and or induction… It shouldn’t be to hard right?
I am in to getting some of this R&D together by the end of the summer, i.e capital for machining and working with Jordan, John and friends to put the pieces together and fool around with clearances. I know there has been talk of part numbers for the rods used? Does anyone have them? Any Swedish Brethren in the house have rods to suggest? Wasn’t there a guy in Oklahoma city who built Claud Hutchins mini stock and motor? Was that guy building the 8v strokers?
Re: 2.5 Monster Motor
Posted: Sat Jul 21, 2012 4:08 pm
by Krasch
Might as well weigh in here. My knowledge of Saab powerplants fades in the early 1990s to no knowledge beyond about 1997.
I am looking to build a better race engine for the 1992 Saab 900 ChumpCar formerly known as Fart-hinder Racing. I have one complete 2.1L very stock and high mileage engine in the car at the moment. I have at least three engine blocks, one of which I intend to build up with donor internal parts from the others.
The tracks we race at -- Brainerd and Road America primarily -- are HP tracks, with long straights where the fastest cars may top out at 120 mph. Consequently anything with a 6-cyl has an advantage (the domestic V8s not so much, oddly enough). BMW 325s dominate, with a couple of V6 Acura Integras, stripped to nothing Hondas, and a couple of overpowered and over-engineered cars from the first ChumpCar season grandfathered in.
We did build a transmission using the primary gears from a 99, figuring that would give us more torque out of the corners. Unfortunately it spun 3rd gear in its first race and has not been rebuilt.
So... where to go? The RBank Saabs have done quite well, but they race at tracks where handling is usually more important, and Claude is doing the work on them. Suggestions welcome. Or should I post this whole discussion as a new thread somewhere?
Re: 2.5 Monster Motor
Posted: Mon Jul 23, 2012 12:18 pm
by Geoff
I saw a 2.5L Turbo motor in a car at the SAAB Festival in Sweden in 2007. It was in a street car. I think it was built just to be the first 16v 2.5L Turbo.
Some things I remember about these big engines in general:
1) The small block Chevrolet rods are the "H" cross section. Not sure if this is for clearance or strength/weight ratio or both.
2) The pistons that the 8v race guys are using are built by Ross. Maybe some clever sleuthing by Ross could come up with the piston which could then be redesigned a little bit for proper compression ratio with whatever 16v head you want to use.
3) There's a ghetto way of building the engine using stock rods and more grinding to the block and transmission case to get clearance.