993 crank expert questions.
11-29-2006, 12:51 PM
#46
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Originally Posted by red993tt
Here's what you need...... 
11-29-2006, 01:02 PM
#47
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beepbeep,
Keep going ! Still be worth getting that compression height information before a dry build. The 993tt uses "small " valves so be careful if you are using late N/A heads. Check the 993tt valve cutouts .
Cylinder pressures are at their highest some way after TDC so its difficult to see what the 993tt piston/head step actually achieves ! I suspect very little .
If the barrel had a step into the head that would make more sense.
There is a possibility that the N/A setup will transfer heat more equally between head and barrel ?
A friend in the UK has made barrels that screw into the heads so no seals needed at all !
Now that is progress but big bucks !
If your setup works maybe it will be a good way to get a low compression N/A motor ?
Keep posting your results. I am interested !!
Geoff
Keep going ! Still be worth getting that compression height information before a dry build. The 993tt uses "small " valves so be careful if you are using late N/A heads. Check the 993tt valve cutouts .
Cylinder pressures are at their highest some way after TDC so its difficult to see what the 993tt piston/head step actually achieves ! I suspect very little .
If the barrel had a step into the head that would make more sense.
There is a possibility that the N/A setup will transfer heat more equally between head and barrel ?
A friend in the UK has made barrels that screw into the heads so no seals needed at all !
Now that is progress but big bucks !
If your setup works maybe it will be a good way to get a low compression N/A motor ?
Keep posting your results. I am interested !!
Geoff
11-29-2006, 01:02 PM
#48
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beepbeep
FWIW, according to my tuner the N/A heads are more efficient than the TT ones, most likely from the port design and valve sizing, albeit the real issue lies in the temp resistence.
Edit: Geoff just saw your post.
Looking at the characteristics of the RR350 Aluminum, it seems to have good stability until 600F (BTW it is also widely used in aircraft applications, which is where I got the info from)..
935Racer
What you highlighted is extremely important, the cylinder head temperature has to be measured at the exhaust ports, since it is the hottest point, and obviously the weakest link. Head temps of 600F means that not much other than the RR350 can be used succesfully on these turbocharged race engines.
So do you think that the best choice out there today for high boosting, or race abused turbo engines are the GT2 EVO heads, since they are made of the highly temperature resistent RR350 and they are the most efficient too, similar to the N/A heads?
Thanks
FWIW, according to my tuner the N/A heads are more efficient than the TT ones, most likely from the port design and valve sizing, albeit the real issue lies in the temp resistence.
Edit: Geoff just saw your post.
Looking at the characteristics of the RR350 Aluminum, it seems to have good stability until 600F (BTW it is also widely used in aircraft applications, which is where I got the info from)..
935Racer
What you highlighted is extremely important, the cylinder head temperature has to be measured at the exhaust ports, since it is the hottest point, and obviously the weakest link. Head temps of 600F means that not much other than the RR350 can be used succesfully on these turbocharged race engines.
So do you think that the best choice out there today for high boosting, or race abused turbo engines are the GT2 EVO heads, since they are made of the highly temperature resistent RR350 and they are the most efficient too, similar to the N/A heads?
Thanks
11-29-2006, 01:24 PM
#49
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The plot thickens!
As I said before, I never ever talked about Turbo heads or Turbo cylinders. It's plain vanilla N/A engine! Only thing Turbo in it will be the pistons!
I survived two pages of Kevin and Rickard telling me I'm crazy and that Turbo pistons never will work in N/A engine. Now information starts to trickle in and I still believe that Turbo pistons in N/A engine might work
Jean & Geoff: thank you for your info. Yeah, that was the point of whole build: plain-vanilla N/A engine, Turbo pistons and some extra stuff.
I'm aware that N/A heads breathes better and has bigger valves. The old engine (964 N/A + Turbo pistons and extra cheese) needed valve pockets machined in cylinders to be able to turn around. I bet ultra long duration/high lift cams dodn't make things easier either.
So the recepy so for is:
Take one slightly used 993 N/A engine. Fit the Turbo pistons and GT3R (or in pinch, standard 993 N/A) crank and H-beam steel rods. Port the heads as much as possible, fit flamerings to make them seal. Fit two Garrett GT35BB's, custom cams and intercooler and good EFI. Fit head temp sensors and never let it go past 220 deg C.
I understand that Turbo heads and cylinders are all the rage, but it seems that we'll be using N/A ones. Old ones never ever leaked...not even @ 2 bar. Actually they sealed so good that one of heads broke in half in one missfortunate missfire, but it never leaked!
VE's and thus BMEP #'s are quite bad high up where this engine lives so i believe sealing shouldn't be such a big issue. I'm more concerned about which crank/rod combo to pick to be able to rev to 7500 without blowing things to pieces.
As I said before, I never ever talked about Turbo heads or Turbo cylinders. It's plain vanilla N/A engine! Only thing Turbo in it will be the pistons!
I survived two pages of Kevin and Rickard telling me I'm crazy and that Turbo pistons never will work in N/A engine. Now information starts to trickle in and I still believe that Turbo pistons in N/A engine might work
Jean & Geoff: thank you for your info. Yeah, that was the point of whole build: plain-vanilla N/A engine, Turbo pistons and some extra stuff.
I'm aware that N/A heads breathes better and has bigger valves. The old engine (964 N/A + Turbo pistons and extra cheese) needed valve pockets machined in cylinders to be able to turn around. I bet ultra long duration/high lift cams dodn't make things easier either.
So the recepy so for is:
Take one slightly used 993 N/A engine. Fit the Turbo pistons and GT3R (or in pinch, standard 993 N/A) crank and H-beam steel rods. Port the heads as much as possible, fit flamerings to make them seal. Fit two Garrett GT35BB's, custom cams and intercooler and good EFI. Fit head temp sensors and never let it go past 220 deg C.
I understand that Turbo heads and cylinders are all the rage, but it seems that we'll be using N/A ones. Old ones never ever leaked...not even @ 2 bar. Actually they sealed so good that one of heads broke in half in one missfortunate missfire, but it never leaked!
VE's and thus BMEP #'s are quite bad high up where this engine lives so i believe sealing shouldn't be such a big issue. I'm more concerned about which crank/rod combo to pick to be able to rev to 7500 without blowing things to pieces.
11-29-2006, 01:33 PM
#50
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Originally Posted by Rickard 993 Turbo
I understand what you mena but the qestion was if the 993tt pistons was protruning in the 993tt head and it does, all years...
That was what we first talked about and what i mean tthat we are sure of, and wha tmy pictures are showing
That was what we first talked about and what i mean tthat we are sure of, and wha tmy pictures are showing
I was aware that turbo cylinders are shorter from very start and tried to explain to you/Kevin troughout two pages that N/A heads and jugs would be used, but you promptly called me unknowledgeable and stone-age.
11-29-2006, 01:56 PM
#51
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Originally Posted by beepbeep
I was aware that turbo cylinders are shorter from very start and tried to explain to you/Kevin troughout two pages that N/A heads and jugs would be used, but you promptly called me unknowledgeable and stone-age.
If you need another set of 993tt pistons to play with I have a used set available although you will obviously have to throw the matching cylinders into the spares pile.
As for crank preferences, in my experience if you are pushing the torque over 750Nm I recommend chosing the larger bearing areas of the GT3R and 964 crank, whereas if you are designing the engine properly by limiting the mid range torque to the above level and extending the torque spread to the redline the 993 n/a crank will probably be fine.
Good luck with your interesting project.
11-29-2006, 02:21 PM
#52
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Originally Posted by beepbeep
No, the real question still is: which crank is best for turbocharged engine turning 7400 RPM's. 993 N/A or GT3R?
If you wish to safely run 7400 RPM, I'd suggest using either the GT3R or 964 crank and doing the oiling mods that improve volume to the #2 & #5 rod bearing journals.
The crank gets cross-drilled, the case oil holes are opened up and the main bearing shell get grooved. We've been doing these modifications since 1979 and haven't lost an engine to rod bearing failure yet. Many of these motors were operated beyond 8500 RPM, too.
Needless to say, one knows to use either the 930 or GT-3R oil pump, Carrillo, Pauter or Arrow rods, and factory (not aftermarket) Glyco rod bearings.
11-29-2006, 02:23 PM
#53
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beepbeep,
2 bar !! That sounds as if the head VE was so crap that the turbos had nowhere to go . The cam profile is so important for monster turbo motors .
Take a look at the standard 993tt profile . Very different to the N/A , more duration and lift . Could be an idea to see how far you get with those cams ??
Just using the latest hod rod N/A cam in a turbo motor generally doesnt work !
Does the EFI system have knock control ? Pretty essential on these motors.
With careful preparation 7500 should not be a problem for a 993 crank .
I would certainly recommend taking a look at Kevins 8500rpm motor build thread .
I always remember the BMW F1 motor , 1500 bhp from 1500cc , in qualifying trim . Memory tells me that 8500 was as far as that one had to rev. Lag was an issue !!
All the best
Geoff
2 bar !! That sounds as if the head VE was so crap that the turbos had nowhere to go . The cam profile is so important for monster turbo motors .
Take a look at the standard 993tt profile . Very different to the N/A , more duration and lift . Could be an idea to see how far you get with those cams ??
Just using the latest hod rod N/A cam in a turbo motor generally doesnt work !
Does the EFI system have knock control ? Pretty essential on these motors.
With careful preparation 7500 should not be a problem for a 993 crank .
I would certainly recommend taking a look at Kevins 8500rpm motor build thread .
I always remember the BMW F1 motor , 1500 bhp from 1500cc , in qualifying trim . Memory tells me that 8500 was as far as that one had to rev. Lag was an issue !!
All the best
Geoff
11-29-2006, 03:47 PM
#54
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Originally Posted by beepbeep
No, the real question still is: which crank is best for turbocharged engine turning 7400 RPM's. 993 N/A or GT3R?
I was aware that turbo cylinders are shorter from very start and tried to explain to you/Kevin troughout two pages that N/A heads and jugs would be used, but you promptly called me unknowledgeable and stone-age.
I was aware that turbo cylinders are shorter from very start and tried to explain to you/Kevin troughout two pages that N/A heads and jugs would be used, but you promptly called me unknowledgeable and stone-age.
gt3r sound like the best crank with a custom rod and your NA stuff then
11-29-2006, 03:51 PM
#55
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Originally Posted by Red rooster
Does the EFI system have knock control ? Pretty essential on these motors.
The car was knocking pretty badly when the y did change intercoolers and pleniums, the car was tuned in the engien dyno before those mods and after that only checked on the street with the new parts, if i rember right something did happend after a testdrive with bad knocking, but beep beep know more about that
11-29-2006, 03:56 PM
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Beepbeep from your picture of the 964 head. It does look like 964 NA heads have been modified.. The perimeter OD has been machined deeper into the combustion chamber. Ala similar to 993TT heads. I've always known the cylinder difference, but with using this combination you need to make up the deck height and piston clearance. Stock rod length are 127mm typically, did you shorten the rod to 126mm?
The previous posts that I have written still holds.. You cannot bolt these parts together without extensive machine work.. It is not a bolt on mod. Basically if I grabbed a NA liner and installed a narrow rod, on a 993 crank or a offset machined rod to fit the smaller piston boss. I could not roll the crank over TDC because the piston would hit the 964 head, even with using the NA liners.
If you use 993NA heads, you will actually have to machine more material out of the combustion chamber, than when using similar 964 heads, due to the flat deck design.
This setup has me intrigued, when I have some time I will mock it up and find out what the exact deck-height measurement needs to be. And see how much material needs to be removed off the piston or combustion chamber. You might want to look for 964NA heads vs 993 heads due to the casting design and higher combustion chamber.
The previous posts that I have written still holds.. You cannot bolt these parts together without extensive machine work.. It is not a bolt on mod. Basically if I grabbed a NA liner and installed a narrow rod, on a 993 crank or a offset machined rod to fit the smaller piston boss. I could not roll the crank over TDC because the piston would hit the 964 head, even with using the NA liners.
If you use 993NA heads, you will actually have to machine more material out of the combustion chamber, than when using similar 964 heads, due to the flat deck design.
This setup has me intrigued, when I have some time I will mock it up and find out what the exact deck-height measurement needs to be. And see how much material needs to be removed off the piston or combustion chamber. You might want to look for 964NA heads vs 993 heads due to the casting design and higher combustion chamber.
11-30-2006, 09:30 AM
#57
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Originally Posted by Kevin
Beepbeep from your picture of the 964 head. It does look like 964 NA heads have been modified.. The perimeter OD has been machined deeper into the combustion chamber. Ala similar to 993TT heads. I've always known the cylinder difference, but with using this combination you need to make up the deck height and piston clearance. Stock rod length are 127mm typically, did you shorten the rod to 126mm?
The previous posts that I have written still holds.. You cannot bolt these parts together without extensive machine work.. It is not a bolt on mod. Basically if I grabbed a NA liner and installed a narrow rod, on a 993 crank or a offset machined rod to fit the smaller piston boss. I could not roll the crank over TDC because the piston would hit the 964 head, even with using the NA liners.
If you use 993NA heads, you will actually have to machine more material out of the combustion chamber, than when using similar 964 heads, due to the flat deck design.
This setup has me intrigued, when I have some time I will mock it up and find out what the exact deck-height measurement needs to be. And see how much material needs to be removed off the piston or combustion chamber. You might want to look for 964NA heads vs 993 heads due to the casting design and higher combustion chamber.
The previous posts that I have written still holds.. You cannot bolt these parts together without extensive machine work.. It is not a bolt on mod. Basically if I grabbed a NA liner and installed a narrow rod, on a 993 crank or a offset machined rod to fit the smaller piston boss. I could not roll the crank over TDC because the piston would hit the 964 head, even with using the NA liners.
If you use 993NA heads, you will actually have to machine more material out of the combustion chamber, than when using similar 964 heads, due to the flat deck design.
This setup has me intrigued, when I have some time I will mock it up and find out what the exact deck-height measurement needs to be. And see how much material needs to be removed off the piston or combustion chamber. You might want to look for 964NA heads vs 993 heads due to the casting design and higher combustion chamber.
We'll see how deck height panes out when pistons and engine appear...
The one that's wrong owns other a beer!
11-30-2006, 09:42 AM
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Originally Posted by NineMeister
The Rennlist 993t forum always makes a special welcome effort for newcomers.
If you need another set of 993tt pistons to play with I have a used set available although you will obviously have to throw the matching cylinders into the spares pile.
As for crank preferences, in my experience if you are pushing the torque over 750Nm I recommend chosing the larger bearing areas of the GT3R and 964 crank, whereas if you are designing the engine properly by limiting the mid range torque to the above level and extending the torque spread to the redline the 993 n/a crank will probably be fine.
Good luck with your interesting project.
If you need another set of 993tt pistons to play with I have a used set available although you will obviously have to throw the matching cylinders into the spares pile.
As for crank preferences, in my experience if you are pushing the torque over 750Nm I recommend chosing the larger bearing areas of the GT3R and 964 crank, whereas if you are designing the engine properly by limiting the mid range torque to the above level and extending the torque spread to the redline the 993 n/a crank will probably be fine.
Good luck with your interesting project.
As I said before, we are just a bunch of amateurs fooling around.
Talking about limiting torque to save the crank:
I did some back-of-the-enevelop calculations on rod forces at peak revs and peak torque and came to conclusion that loads are greatest at high revs, not at peak torque RPM's. Of course, BMEP and piston crown pressure would be greatest at torque peak but inertial loads, being exponential, will take over and surpass the combustion forces at peak revs?
So I guess that maximum engine speed issue is the one that should be adressed with greatest care, no?
993TT pistons have been great so far. Pieces that were installed in old engine were used to begin with. They survived multiple overrevs, bent valves, hilarious boost pressures and backfires. We are still unable to tell what when wrong on the ring: was it piston that cracked and beat the crank bearing or crank bearing that spun and beat wrist-pin to submission.
11-30-2006, 11:37 AM
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Beepbeep, you are right about the forces on the rod. Although it may seem strange, a high reving normally aspirated engine will subject the rod to a greater load due to the inertia loads. In addition, you must not forget about the Coriolis force!
By the way, love the egg shaped carrillo!!!I not managed to do thiswith a steel rod but have ruined a couple of Ti rods in the same manner. I put it down to oil starvation, then heat then a pain in the wallet! My piston was still intact, although badly beaten, so I dont think the issue was at that end of the rod. I have broken a rod at the little end and there was not much left of the engine! I was using some very special (I designed them) Ti rods and they just were not strong enough! What was left of the engine was cut in half by the rod - not a pretty site and the ensuing fire didn't do the car much good either!
All I can say is "amateurs rule OK"!!!!!!!
Keep on playing, its amazing what you can do.
Cheers,
Richard.
By the way, love the egg shaped carrillo!!!I not managed to do thiswith a steel rod but have ruined a couple of Ti rods in the same manner. I put it down to oil starvation, then heat then a pain in the wallet! My piston was still intact, although badly beaten, so I dont think the issue was at that end of the rod. I have broken a rod at the little end and there was not much left of the engine! I was using some very special (I designed them) Ti rods and they just were not strong enough! What was left of the engine was cut in half by the rod - not a pretty site and the ensuing fire didn't do the car much good either!
All I can say is "amateurs rule OK"!!!!!!!
Keep on playing, its amazing what you can do.
Cheers,
Richard.
11-30-2006, 09:17 PM
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sorta related.... I assume most of the folks running grooved/cross drilled cranks have the low RPM oil pressure issue i do...I try to cool down tooling around the neighborhood or decelerating down hills with no throttle... specifically since it kills me to idle with virtually no oil pressure... any thoughts??
... and beep beep... since you want big boost.. if you do get '94 3.6 or 3.8 turbo pistons to go with your NA liners.... please note the compression is MUCH higher on them... generally on the order of 8.7-8.9 to one.... 2 bar and 8.9 would be fun to watch.... 'fire in the hole' :-)
... and beep beep... since you want big boost.. if you do get '94 3.6 or 3.8 turbo pistons to go with your NA liners.... please note the compression is MUCH higher on them... generally on the order of 8.7-8.9 to one.... 2 bar and 8.9 would be fun to watch.... 'fire in the hole' :-)