95 C4 3.8 build
05-04-2015, 08:11 AM
#16
I used the RSR Mahles, the 109mm bases have a more robust seal that the 3.6 and bore in 107's lack. The big bores push a lot of air around internally, the GT3 runs the cc below atmospheric as an even better solution but needs the GT3 oil pump, special seals and a special breather valve. The RSR's also have nifty l/w tapered bore wrist pins, every gram you save in reciprocating weight is critical. If you can get the sets w/ asymmetrical wristpin o/s that is a +, I have the old symmetrical ones they are supposed to have more piston slap but I haven't noticed it, maybe if I could hear both sets side buy side it would be more obvious.
a friend has a supercharger kit on his track only 993, got to admit that it is very nice w/ a unique sound, the only problem was a spin that blew the intake off the engine, but I have seen that on n/a too.
a friend has a supercharger kit on his track only 993, got to admit that it is very nice w/ a unique sound, the only problem was a spin that blew the intake off the engine, but I have seen that on n/a too.
05-04-2015, 08:03 PM
#17
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Seriously, I'm not feeling it with how you've described what a shop is telling you, your questions, and it's translating in the thread. Talk to Steve Weiner, pretty much end of story.
I've got what everyone proposes for their car, and it came to nearly $80K in 2003 for the guy who had the car and spent the money.
I am definitely going for the bore in 3.8 P and C per your recc and the case work is not much more anyway and I want to be safe.
I will also keep the redline 6800 per your note.
What else, specifically is bothering you about the build?
05-04-2015, 09:30 PM
#20
Race Car
Lots of good advice here...
If you raise the rev limit to 7k, then a set of ARP bolts are all that you will need.
To go above, even just a little there is alot of extras that need to be adjusted, and with that the cost really sky rockets, as you start to touch more and more of the engine.
A 7500 rpm engines as you eluded to is really going to need rods, valve springs, retainers etc, GT3 Crank, GT3 Oil pump etc. All these are necessary to keep the engine in one piece and have a decent life expectance for it. However to make use of the extra RPM you need cams, and probably a set of solid rockers as the Cams that will work at the higher RPM won't work with the hydraulic rockers.
Even the RS cams are really only good for 7000 rpm MAX.
You also run into issues with the plastic intake, these start to run into a supply issue at higher RPM in larger capacity engines. I was finding it really limited my engine's top end power, I am at 4.0l which is a big jump from the 3.8 set (almost 250 CC larger than a RS 3.8)
The other issue you then face is fuel delivery etc, stock injectors are just not up to the task, we even found issue with some 36lb Injectors (Stock are approx 26lb).
Now you are looking at starting to go beyond the ability of the stock ecu to manage the fuel etc.
The slope is near vertical, I know.... Been there done that and still sliding.......
If you raise the rev limit to 7k, then a set of ARP bolts are all that you will need.
To go above, even just a little there is alot of extras that need to be adjusted, and with that the cost really sky rockets, as you start to touch more and more of the engine.
A 7500 rpm engines as you eluded to is really going to need rods, valve springs, retainers etc, GT3 Crank, GT3 Oil pump etc. All these are necessary to keep the engine in one piece and have a decent life expectance for it. However to make use of the extra RPM you need cams, and probably a set of solid rockers as the Cams that will work at the higher RPM won't work with the hydraulic rockers.
Even the RS cams are really only good for 7000 rpm MAX.
You also run into issues with the plastic intake, these start to run into a supply issue at higher RPM in larger capacity engines. I was finding it really limited my engine's top end power, I am at 4.0l which is a big jump from the 3.8 set (almost 250 CC larger than a RS 3.8)
The other issue you then face is fuel delivery etc, stock injectors are just not up to the task, we even found issue with some 36lb Injectors (Stock are approx 26lb).
Now you are looking at starting to go beyond the ability of the stock ecu to manage the fuel etc.
The slope is near vertical, I know.... Been there done that and still sliding.......
05-04-2015, 10:10 PM
#21
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I updated the main post to reflect the new build, but in short:
I am keeping the stock rods with ARP bolts
I am going for the 109 P and C set and doing the case work
I am keeping the stock redline
I am going for uprated valve springs (but not titanium or anything)
Sticking with the RS hydraulic cams
Thanks for your help and comments all! Feel free to throw out any other ideas for while you are in there stuff
05-05-2015, 03:28 AM
#23
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05-05-2015, 03:34 AM
#24
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Per my research, this is to help prevent valve float and also to give me a little extra protection. The cost of the springs is not much compared to new stock springs. Not sure if it is worth it, but I don't want to skimp on such a small thing. That said, obviously I am not the expert. Here to learn from you guys and search the forum for the great info here.
05-05-2015, 03:41 AM
#25
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05-05-2015, 04:01 AM
#26
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Lots of good advice here...
If you raise the rev limit to 7k, then a set of ARP bolts are all that you will need.
To go above, even just a little there is alot of extras that need to be adjusted, and with that the cost really sky rockets, as you start to touch more and more of the engine.
A 7500 rpm engines as you eluded to is really going to need rods, valve springs, retainers etc, GT3 Crank, GT3 Oil pump etc. All these are necessary to keep the engine in one piece and have a decent life expectance for it. However to make use of the extra RPM you need cams, and probably a set of solid rockers as the Cams that will work at the higher RPM won't work with the hydraulic rockers.
Even the RS cams are really only good for 7000 rpm MAX.
You also run into issues with the plastic intake, these start to run into a supply issue at higher RPM in larger capacity engines. I was finding it really limited my engine's top end power, I am at 4.0l which is a big jump from the 3.8 set (almost 250 CC larger than a RS 3.8)
The other issue you then face is fuel delivery etc, stock injectors are just not up to the task, we even found issue with some 36lb Injectors (Stock are approx 26lb).
Now you are looking at starting to go beyond the ability of the stock ecu to manage the fuel etc.
The slope is near vertical, I know.... Been there done that and still sliding.......
If you raise the rev limit to 7k, then a set of ARP bolts are all that you will need.
To go above, even just a little there is alot of extras that need to be adjusted, and with that the cost really sky rockets, as you start to touch more and more of the engine.
A 7500 rpm engines as you eluded to is really going to need rods, valve springs, retainers etc, GT3 Crank, GT3 Oil pump etc. All these are necessary to keep the engine in one piece and have a decent life expectance for it. However to make use of the extra RPM you need cams, and probably a set of solid rockers as the Cams that will work at the higher RPM won't work with the hydraulic rockers.
Even the RS cams are really only good for 7000 rpm MAX.
You also run into issues with the plastic intake, these start to run into a supply issue at higher RPM in larger capacity engines. I was finding it really limited my engine's top end power, I am at 4.0l which is a big jump from the 3.8 set (almost 250 CC larger than a RS 3.8)
The other issue you then face is fuel delivery etc, stock injectors are just not up to the task, we even found issue with some 36lb Injectors (Stock are approx 26lb).
Now you are looking at starting to go beyond the ability of the stock ecu to manage the fuel etc.
The slope is near vertical, I know.... Been there done that and still sliding.......
Bottom line, the extra torque will be welcome.
I did explore the larger 3.9-4.0 P and C but it is a whole other world up their with rods, titanium springs and retainers, updated bearings, GT3 oil pump, oiling mods, GT3 crank, lumpy solid lifter cams, better injectors, intake, ECU, ITB, 9M Heads etc etc in the 30k++ build range lots of things happen very fast. My build is mostly stock with a few key mods and not that much more than a standard rebuild. I don't care much about the cost difference because it is what I want and I will have a brand new motor I don't need to worry about.
Thanks again for all this info and sharing your story and experience.
05-05-2015, 10:28 AM
#27
Race Director
hmm, your build feels a bit conflicted.
I'm not necessarily sure what i'd change, but i'd probably either further to the race end or stay with a stock displacement and some head/cam work.
I'm not necessarily sure what i'd change, but i'd probably either further to the race end or stay with a stock displacement and some head/cam work.
05-05-2015, 11:18 AM
#28
Rennlist Member
^ Agreed. It has been shown that a properly rebuilt 3.6 with head and cam work performs very close to a 3.8L.
I would put the rest of the money into a gearbox regear and rock it for the next 120K miles or if get bored in 50K miles, then add a supercharger.
I would put the rest of the money into a gearbox regear and rock it for the next 120K miles or if get bored in 50K miles, then add a supercharger.
05-05-2015, 12:39 PM
#29
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Planning:
3.8 bore in 109 P and C
RS cams and better springs
Head work (port and polish, new valve seats)
Stock rods with arp rod bolts
Oil pump mods
Main bearings and rod bearings
IMS shafts
Oil thermostat
Misc Etc per stock rebuild
Chip
Clutch kit with master and slave cylinders
Phase 2
Re-gear
AASCO LWFW
Etc.
Possible Phase 3
Intake
ECU
Tuning
05-05-2015, 01:04 PM
#30
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I am not hung up at all on the extra cost for P and C and case work. Also I am going to do a re-gear within the next year or two as well.
What specific parts outside of what I list do you think are needed?
This is a street car with the stock redline to be used as our daily driver.