3.8L Twin Turbo conversion
09-30-2015, 12:55 PM
#1
Instructor
Thread Starter
3.8L Twin Turbo conversion
Ok, so I decided to turbo charge the 3.8l that I have installed in a 95' C4. The car is used for track only so Im guessing the right turbo for the application should be mid to top range spool. Looking to make 14psi which should bring the compression to 12:1 for 93octane.
Any recommendation on turbos to be used?
k24/16, k26/24, gt3076, ETC.
Reusing:
1. Web/Cam club sport cams with 15K miles on them
2. WebCam mechanical lifters with 15K miles on them
3. Valves (Upon inspection)
4. Valve guides (Upon inspection)
5. Valve springs (Upon inspection)
Shopping list:
1. 3.8L Pistons/cylinders Compression 8.3:1
2. Replacing rods with Carillo,
3. APR studs
4. Fuel pump (73PSI)
5. Fuel pressure regulator
6. New injectors
7. Oil backflow kit for turbo oil feed line
8. Intercooler, piping
9. Waste Gates
10. Blow off valve
11. Turbos
12. turbo headers (side mount or rear)
13. Protomotive chip
14. Boost gauge
15. ??
What else am I missing?
Any recommendation on turbos to be used?
k24/16, k26/24, gt3076, ETC.
Reusing:
1. Web/Cam club sport cams with 15K miles on them
2. WebCam mechanical lifters with 15K miles on them
3. Valves (Upon inspection)
4. Valve guides (Upon inspection)
5. Valve springs (Upon inspection)
Shopping list:
1. 3.8L Pistons/cylinders Compression 8.3:1
2. Replacing rods with Carillo,
3. APR studs
4. Fuel pump (73PSI)
5. Fuel pressure regulator
6. New injectors
7. Oil backflow kit for turbo oil feed line
8. Intercooler, piping
9. Waste Gates
10. Blow off valve
11. Turbos
12. turbo headers (side mount or rear)
13. Protomotive chip
14. Boost gauge
15. ??
What else am I missing?
10-09-2015, 12:20 AM
#3
Rennlist Member
I can help you on that path. I currently have a C4S turbo conversion. About 600hp at the moment.
GT2867 Turbos, No questions. I played with them all.
Heads will need to be welded and flame ringed
I would question reusing the cams. GT2 cams with 113-115 lobe centers work best. Talk to John Dogerty about DC21's.
I would not recommend the 3.8 kit. Stick with the 3.6 for better head seal. Get the Porsche Motorsports barrels and pistons.
Check with Todd at Protomotive. Nobody has done more conversions than he has.
Here is mine at 8psi tapering to 6psi.
I have since added a boost controller and hold 11psi to redline. About 500whp/600crank
Gt2860 turbos, DC21 cams, Stock 11.2 pistons, Arrow Rods and welded/flame ringed heads.
GT2867 Turbos, No questions. I played with them all.
Heads will need to be welded and flame ringed
I would question reusing the cams. GT2 cams with 113-115 lobe centers work best. Talk to John Dogerty about DC21's.
I would not recommend the 3.8 kit. Stick with the 3.6 for better head seal. Get the Porsche Motorsports barrels and pistons.
Check with Todd at Protomotive. Nobody has done more conversions than he has.
Here is mine at 8psi tapering to 6psi.
I have since added a boost controller and hold 11psi to redline. About 500whp/600crank
Gt2860 turbos, DC21 cams, Stock 11.2 pistons, Arrow Rods and welded/flame ringed heads.
10-09-2015, 03:37 PM
#6
Rennlist Member
I am running Dogerty DC21 cams with 115 lobe centers. This helps bleed off static compression of the stock 11.2 pistons. Your cam requirements will be different with the 8.7CR. The GT2 cams will be perfect.
I am dual plugged. My build is all based around a stock VRAM motor.
I am dual plugged. My build is all based around a stock VRAM motor.
10-09-2015, 08:28 PM
#7
Instructor
Thread Starter
Marin,
Thanks for the heads up on GT2 Cams, the motor that is being converted is already 3.8L and I have already sourced the 3.8 pistons to lower the CR TO 8.3. I'm looking for someone that can fabricate the headers for a rear turbo mount and the intercooler with brackets. I have a really good quote from TTP (Turbo Tuning Pietz) GmbH for their 993 RS 3,8l Twinturbo conversion EVO that puts out 550hp at the wheels with racing K24. The kit includes injectors, fuel pump, fuel regulator the small stuff that you don't get here with the US kits. Who made your headers and the intercooler? Mark
Thanks for the heads up on GT2 Cams, the motor that is being converted is already 3.8L and I have already sourced the 3.8 pistons to lower the CR TO 8.3. I'm looking for someone that can fabricate the headers for a rear turbo mount and the intercooler with brackets. I have a really good quote from TTP (Turbo Tuning Pietz) GmbH for their 993 RS 3,8l Twinturbo conversion EVO that puts out 550hp at the wheels with racing K24. The kit includes injectors, fuel pump, fuel regulator the small stuff that you don't get here with the US kits. Who made your headers and the intercooler? Mark
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10-09-2015, 09:52 PM
#8
Rennlist Member
John at Prototech in Florida.
K24's are old turbos that are not great for your application. If you're hell bent on em at least upgrade the compressor to a Super 60T3, 67mm Garrett of 68mm Tial. Those compressors are much better suited to a 3.8 running 14psi of boost. I would lean towards the super 60t3 based on what you describe.
K24's are old turbos that are not great for your application. If you're hell bent on em at least upgrade the compressor to a Super 60T3, 67mm Garrett of 68mm Tial. Those compressors are much better suited to a 3.8 running 14psi of boost. I would lean towards the super 60t3 based on what you describe.
10-09-2015, 10:20 PM
#9
Instructor
Thread Starter
John, I'm not "hell bent" on K24 but TTP's kit includes "Special modified k24 racing turbos" which sound like they're already upgraded. I will ask on Monday for more details on them.
Back to the cam shafts, what I have are 993 super sport web cams Grind #296 set @1.55mm/.10mm lash and I see that FVD is selling the same setup for Bi-turbo application on 993tt993gt2. With the information provided above, do you still think there's a need for upgrade?
Back to the cam shafts, what I have are 993 super sport web cams Grind #296 set @1.55mm/.10mm lash and I see that FVD is selling the same setup for Bi-turbo application on 993tt993gt2. With the information provided above, do you still think there's a need for upgrade?
10-09-2015, 10:41 PM
#11
Rennlist Member
I don't have enough info on the cams or the turbos to offer a opinion.
Get together with someone and do the math for lift, duration, overlap, IVC and dynamic compression ratio for the cams. That will tell you if they're properly suited for your project or not.
Find out what compressor they are running on the turbo and plot your info over the compressor MAP. Compare that with the others I suggested and decide if they are the best option.
I know these are not the answers you're looking for but trust me if you do the proper research the results will better than just copying what others do.
Get together with someone and do the math for lift, duration, overlap, IVC and dynamic compression ratio for the cams. That will tell you if they're properly suited for your project or not.
Find out what compressor they are running on the turbo and plot your info over the compressor MAP. Compare that with the others I suggested and decide if they are the best option.
I know these are not the answers you're looking for but trust me if you do the proper research the results will better than just copying what others do.
10-10-2015, 08:49 PM
#12
I can help you on that path. I currently have a C4S turbo conversion. About 600hp at the moment.
GT2867 Turbos, No questions. I played with them all.
Heads will need to be welded and flame ringed
I would question reusing the cams. GT2 cams with 113-115 lobe centers work best. Talk to John Dogerty about DC21's.
I would not recommend the 3.8 kit. Stick with the 3.6 for better head seal. Get the Porsche Motorsports barrels and pistons.
Check with Todd at Protomotive. Nobody has done more conversions than he has.
Here is mine at 8psi tapering to 6psi.
I have since added a boost controller and hold 11psi to redline. About 500whp/600crank
Gt2860 turbos, DC21 cams, Stock 11.2 pistons, Arrow Rods and welded/flame ringed heads.
GT2867 Turbos, No questions. I played with them all.
Heads will need to be welded and flame ringed
I would question reusing the cams. GT2 cams with 113-115 lobe centers work best. Talk to John Dogerty about DC21's.
I would not recommend the 3.8 kit. Stick with the 3.6 for better head seal. Get the Porsche Motorsports barrels and pistons.
Check with Todd at Protomotive. Nobody has done more conversions than he has.
Here is mine at 8psi tapering to 6psi.
I have since added a boost controller and hold 11psi to redline. About 500whp/600crank
Gt2860 turbos, DC21 cams, Stock 11.2 pistons, Arrow Rods and welded/flame ringed heads.
Are you "cooling" your BB turbos with oil instead of water?
10-11-2015, 04:04 PM
#13
Rennlist Member
Yes. The feed to the bearing oil side is very restricted. I forget the size but it's what Tial/Garrett recommended.
The cooling side is also fed oil and restricted. I know some guys will just cap those off (I considered that too) but having oil move through there is much better for turbo life. The new Garrett's (GTX family etc) have steel bearing cages so it's less sensitive but I'd still do it anyway.
If I were to guess I would say 1mm hole for ball bearings and 4mm hole for cooling. If you're serious I'll dig up the info for you. This setup has been running VERY strong for 6+ years.
The cooling side is also fed oil and restricted. I know some guys will just cap those off (I considered that too) but having oil move through there is much better for turbo life. The new Garrett's (GTX family etc) have steel bearing cages so it's less sensitive but I'd still do it anyway.
If I were to guess I would say 1mm hole for ball bearings and 4mm hole for cooling. If you're serious I'll dig up the info for you. This setup has been running VERY strong for 6+ years.
10-11-2015, 11:06 PM
#15
Banned
16/16g
Get a Set of 16/16g's From Todd Or see if Sam has some, One of the best set ups for 993TT Budget wise, This is a conservative load-bearing Dyno on 91oct with 17.5 ish PSI, This car was FAST, http://www.ebay.com/itm/Porsche-993-...0460a5&vxp=mtr
