I have 10.6:1 compression due to a milled head and 9.8C pistons. Whats your opinions on running and intercooled 5-6lbs of boost with that compression (I'm gonna do it anyway but you can always say "I told you so" later"). My logic is if you can run 17psi on 9:1 and pump gas then 10.6:1 and 6psi shouldn't be all that unfeasable (albeit less powerful). That an the fact that I've run 70hp nitrous on the same compression with no problems (although it intercools like no intercooler can). Believe it or not I plan on 10.6:1 compression, 6lbs of boost and a 50hp shot.
#1575, "RE: High compression and boost" In response to Reply # 0
I think running 5-6 psi boost at that high compression should be OK, eventhough, it's more risky. But then again, turbo charged, high compression Integras are fairly stable at about 7 psi boost. My .02 cents.
Speaking from no personal experience at all, Stan. But I'd say what the hell and go for it. I would highly recommend being intercooled at that amount of boost and do other things to safeguard detonation. These measures could include compensating more fuel, being interooled like hell (USE FMIC for sure), maybe get a MID-2 or Crane ignition and be able to turn the ignition timing back some, and of course use colder plugs. All things considered, you'll still be taking some chances, but I'm sure it can be done. After all, I've heard those porsches come stock with 10:1-like CR's and seem to hack, with add'l safeguards in place I'm sure.
Maximum boost (C. Bell) talks about in his book how CR interrelates with boost and draws an exponential graph on what is safe boost in relation to your CR. Their graph takes into account the efficiency of the intercooler in relation with boost pressure as to safe boost amounts.
Good luck and boost on!
Jason 98' Eagle Talon ESi-T Mitsu Super 16g Turbo(HRC)
I also think you should be fine with 5-6 psi, but are you sure you gonna keep your hand OFF the boost knob?
ever thought about getting thicker head gasket?
ah and make sure you get WG that will allow you to go that low on PSI.
one more thing, in your case I would go with SMIC since you only gonna be running 5 psi, bigger is better if you are planning to turn the boost up, but again you might be looking at pressure loss and turbo lag if you gonna put huge IC
#1578, "RE: Here's my .02" In response to Reply # 3
Yeah this would only be a temperary set up until I can replace the headgasket with a thicker one. I definately wouldn't feel comfortable running this way without an intercooler. I thought about the ignition too to cut back on timing with boost but I may do that on an as needed bases.
#1579, "RE: Here's my .02" In response to Reply # 4
You should retard the timing as mentioned with an MSD or Crane ignition. We have actualy run as much as 11:1 compression in other 35 PSI racing applications. Now, that presumes the use of ultra-high octane gas, but you get the idea: with correct fuel mixture and ignition management, you can do it.
One aspect of the 420A that I find particularly tasty is its ability to resist detonation due to its superior head and combustion chamber design. Now, of course even this excellent design has its limits if mis-tuned, but I have found it to be a most forgiving engine if I play by the rules.
Bill Hahn Jr. 98 RS Turbo: 10.87 @ 136 MPH HRC Stage V with N20 Nation's Fastest Street FWD 2G DSM www.turbosystem.com
#1582, "RE: Here's my .02" In response to Reply # 7
Personal thoughts on both matters:
The only water injection kit worth getting is the aquamist - go to aquamist.co.uk - Water injection is good for providing extra safety, but not for trying to make more power on a stock bottom end. The biggest advantage is it will allow you to turn the boost up on pump gas. It is like running higher octane fuel all the time. Or it will allow you to be safer at a lower boost level, but it doesn't do anything for you power wise really at that boost level.
Total Seal Rings - I considered these when doing my rebuild, but they seem to be more hype than anything to me. Not that they don't do what they advertise, but because a little blow by on a street car is not really all that bad. The total seal rings cost twice as much and I still have not seen where it helps engine longetivity or is necessary for making large amounts of power. The JE rings seem fine to me.
#1583, "RE: Here's my .02" In response to Reply # 8
Yeah everybody has a different opinion on rings. I dont think it really matters too much either. I checked all the racing V8 rings and all the supposedly good ones from every brand were ductile iron rings coated with some kind of plasma moly. The total seals were made of the same materials and I needed all the blowby resistance I could get with .005" clearance. I dont know about longevity but for years they came with 100K warranties. I haven't seen that advertised lately.
#1584, "RE: Here's my .02" In response to Reply # 7
I have found water injection to be a bit edgy, for as you adapt the tuning of the car to take advantage of it, the car then also becomes dependent upon it to resist detonation. Then, if the water injection system fails or simply runs low on water, engine damage from detonation may result. I prefer correct conventional tuning instead.
We have not seen any advantages in dyno or track testing with the Total Seal rings. I attribute this to the fact that the actual leakage path on a standard ring is .003" x .012", which is .000024 square inches: not very much at all, and compression or combustion pressures need to travel through two such gaps to actually get past the rings. Actual leakage therefore becomes almost unmeasurable.
Bill Hahn Jr. 98 RS Turbo: 10.87 @ 136 MPH HRC Stage V with N20 Nation's Fastest Street FWD 2G DSM www.turbosystem.com
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