View Full Version : NG turbo in to c900
chief 900aero
02-05-06, 12:56 PM
can you simply drop a ng900t motor in to an c900 1991 on wards with out any major moderfications??:roll:
The engine in the NG900 is the other way around, i can never remember which is transverse and which is inline, C900 transverse maybe?
No, the c900 is in line (front to back) the gm900's are transverse (side to side).
Maybe you could do it if you mounted it midship:D
I'm sure this has been done to death but can you fit any of the NG900 heads onto a C900 block?
it has probably been done but i dont see much reason for doing it. the c900 engine is a strong one and with a little tuning can produce the results :) as far as mounting a ng900 head on a c900 head goes, i know its been done. just a month ago i talked to a guy that had a 9-3 head on his c900. its not worth it unless you are real serious though as you will need to have a lot of stuff made custom. if you are just looking for better airflow put a post 91 c900na 2.1L head on (27% better airflow or something along those lines). what it comes down to is there are many ways to make a c900 quite powerful without going to the extremes of switching heads or engines :lol:
Eric van Spelde
02-05-06, 02:49 PM
what it comes down to is there are many ways to make a c900 quite powerful without going to the extremes of switching heads or engines :lol:
That's not what it's about. What it's about is to make the prodigious power and torque numbers Saab turbo engines are capable of, work with the car rather than against it. The sledgehammer approach has been used often enough, and the result is invariably a car that a) breaks stuff all the time and b) isn't that enjoyable to drive at the times it isn't broken.
What's needed is: 1) better throttle response and b) a wider useable RPM band. 1) Involves speccing lighter internals, lower friction valve train components, lighter flywheel, as well as shortening/derestricting the intake path; all of which are contributing factors to achieving 2), in addition to achieving better flow. Enter the T7 head, which offers lighter, low-friction valve train components as well as the absolute best flow properties of all 'real' Saab heads.
Yes, you can achieve similar bhp numbers with just bloting on a big turbo and cramming in big boost (provided adequate fueling), and no, it won't be the same as a properly built engine making good use of available later technology.
Another thing: 15 years ago someone here built a 270 hp 99T16. It went through a succession of owners as it did about 10-12 mpg, something of which one quickly grows tired. My 280 hp 900 using the T7 head and DI ignition amongst other things, does twice that easily even using the short #6 primary gearing on a late-model gearbox...
Eric, if at some point in the future i upgrade my 8v head to a 16v is it worth while going straight to the T7 head and not bothering with the c900 16v head?
If it has'nt been listed off before could you give a rough idea of what needs to be modified to do the swap.
Cheers.
Eric van Spelde
02-05-06, 03:44 PM
The main problem I see with dropping a later head on a B201 engine is that with the stock pistons on those, the static compression ratio will drop rather too far for useful off-boost performance, where an '86-'93 head on a T8 will bring you into the 8.25:1 range, which is pretty much bang on for a high performance/high boost turbo mill. With the B212/234 ('90-'93) head you'll drop to 8:1 or a shade lower, whilst a T5 or T7 has bigger combustion chambers still - I'd guesstimate you'd be in the 7.7:1 range or thereabouts.
Physically, dropping a shortblock head on a longblock engine involves modifying the timing chain end on the head (basically welding in new material and planing the head afterwards), tapping an extra bolt hole for right hand side engine mount or PS pump bracket I think (I forgot), modifying RHS engine mount, and a different intake manifold (mine is custom, but it seems one can get away with a ported B212 intake if one redrills the bolt holes). At the exhaust side everything bolts up and matches as per usual.
T7 heads have basically the same casting as the T5 IIRC, but flow better due to the thinner valve stems (and a a consequence, valve guides being less of a restriction in the intake/exhaust path). The valve gear is all new, lighter valves through thinner valve stems, with lighter valve springs giving less friction -> not so good for ultra,megaboost applications but good for rev-ability and response.
just nab a shortblock from an lpt Si, t7 head, start mounting it on. Meantime, turn the boost way up on the t8 :)
Meantime, turn the boost way up on the t8 :)
Well i'm prob going to pick up a T3/T4 trim 60 hybrid in the next few days:cool: , so will be boosting 21psi + soon!
I'll either carry on and get a fast road cam & Ford pinto intake valves for the 8v or move straight onto a 16v head, or like you said, pick-up an lpt block and sort out a T7 head for it.
chief 900aero
04-05-06, 11:43 AM
ok, im sorry to sound dumb but whats a T7? im new to saabs and as i havent even got my l's yet its my 1st car. saying that i have pulled a 82 900 apart and together and this one is way beter lol.
The T7 will be the head off a later 16v NG 900, so will be more refined than the c900 16v head.
Eric van Spelde
04-05-06, 01:02 PM
The T7 will be the head off a later 16v NG 900, so will be more refined than the c900 16v head.
No, that's a T5. T7 heads are on all 9-5's and 2000-on 9-3's.
chief 900aero
04-05-06, 01:19 PM
T5 isv that easy to fit to my 2.1n/a 1993
Eric,
I thought there was a cam timing issue b/c the center distance of the cams to the block was different between a C900 2.0/2.1 head and a T5/T7 head. Can you confirm or deny this? Any issues on this end?
As you may know, I am running DI on my C900 with Megasquirt, so do not have to worry about a dizzy. I have been thinking of this project for a while. With the sludged T-7s around here, T7 heads should be easy to come by at a reasonable price :).
KeithG
Keith/Eric, as the Saab 16 heads are very similar does this allow you to run the DI on a 900 16v engine? I'm mainly asking cos i assume that you could'nt DI a 8v as the plugs would be spaced differently and the DI would be on the hot side of the engine.
Am i on the right lines?
Saab-Daniel
09-05-06, 04:41 PM
8v's wont be able to run DI. All t16's kan have a DI-fitted...
Daniel.
I thought there was a cam timing issue b/c the center distance of the cams to the block was different between a C900 2.0/2.1 head and a T5/T7 head.
T5 head is thinner than B2x2 (sorry, spec at home), which affects cam timing (retards the cams). But use T5 cams and it shouldn't be an issue.
however, there is no T5 or later intake cam with similar duration to B202T intake. Thus, you will run higher dynamic compression with a later cam.
If using a distributor, for exhaust cam, use one from NA mid-90s NG900 non-turbo (Motronic = distributor = slotted cam).
When I put my T5 head on, I made the newb mistake of not cc'ing it. For a long time I was under the impression that the chambers are at 50cc; however, I have since learned that they may actually be more in the neighborhood of 44-45cc. I have access to T5 heads but haven't had the time to go cc one...
You might be able to use the later cam gears on a B2x2 + shortblock head (they have a different offset). This would allow you to run the commonly available adjustable gears with both B2x2 cams or a B2x2 intake cam. Of course, swapping the lower gear off the crank is non-trivial.
You can use your flywheel as a degree wheel if you have access to AutoCAD: make a strip of paper whose length = flywheel circumference, mark it off with degrees, wrap it around flywheel periphery, and line up 0* on the paper with 0* on flywheel. Test away.
ok, im sorry to sound dumb but whats a T7? im new to saabs and as i havent even got my l's yet its my 1st car. saying that i have pulled a 82 900 apart and together and this one is way beter lol.
"T" refers to Trionic engine management, introduced in the early 90s. T5 was a version used on engines in the mid-90s, and T7 was a later version of Trionic used on even newer Saabs (the current version is T8). So, for example, a "T5 head" refers to a head made during the period when the engines ran Trionic 5.
T5 heads are sometimes referred to as "shortblock" heads because the newer engines (beginning 1994 IIRC) to which they were fitted were physically shorter than the older ones by about a 1/2-inch.
You cannot use a B204L engine from an NG 900 in the C900. The NG900 and 9000 after 1993 use a straight block, not angled at 45 degrees like the C900 and early 9K.
As a result the head will poke out the hood and potentially the crank will hit the gearbox (I think that's only on a 2,3).
I still say stuff it midship and go RWD. Better yet use a 9000 Aero mill.
Well then just put a 572-R :cheesy: :cool: :D