R
Reddragon800
Well-known member
You can just do the new billet throttle bodies and injector relocate on an 850 and makes 15hp.
9R Build - high compression head with twins, billet throttle bodies and injector re-locate
- Thread starter Reddragon800
- Start date
Would the 9R see hp increases with just the billet throttle bodies and injector relocate?
R
Reddragon800
Well-known member
Yes it would. it would be roughly 15hp
I have been telling people they are turning their 9R's to tight. I found adding 4 grams to my 23 9R's clutch got me at 8100 and a much better pulling machine. I also have not changed my clutch yet for the new one and have not fouled a single plug. Over 1000 miles on it.
Curiosity question about the upshift403 mod. Looking at my stock 850 it appears the injector shoots directly into the rear transfer port. I thought the advantage of this was that it doesn't wash the oil off the bearings so the snowmobile can use less oil. On the other hand I can see how injecting fuel through the throttle bodies would help cool the bearings down. Throttle body injection would also allow the fuel more time to vaporize. My understanding is you want cool air but actually "warm" fuel so it vaporizes and burns completely. So running fuel through the throttle bodies and hence the entire bottom end kills two birds with one stone, cools the bearings, and warms the fuel. Only down side I can see is potentially washing oil off the bearings?
Interesting. I thought it was cool air and fuel made more power. It was in reference to v8s but I recall a dyno shoot out of a Port injection vs TBI vs Carb. The TBI and Carb made more power because the fuel/air ration cooled more before it hit the combustion chamber.
The tunnel ram on my boat is cool to the touch after a long pull on a hot summers day. So I think there is something to that
Transfer port injection is more efficient, although it varies a lot, depending on engine speed and load. That's because it allows you to time the injection during the intake/exhaust cycle to minimize raw fuel going out the exhaust. As I recall from some of Dan's discussions, the downside is two-fold, with the rod bearing taking it hardest. First was mentioned: the fuel in the crankcase helps keep the rod bearing cool. Second, it helps lubricate the rod bearing because there's far more lubricant (fuel/oil mix) in the case, where the rod bearing is left with what little oil can be maintained in the case. The main bearings have it a lot easier because they're fed oil directly. As for washing oil out, that's really not a problem as long as it isn't raw gas. Old school engines ran just fine (generally longer, if anything) on pre-mix. I'm not sure of the atomization part of it - it may actually be worse because fuel returns to a liquid state pretty easily. That's part of the reason automotive engines moved from TBI to port to direct injection - although the advantage is usually more in fuel efficiency than raw power.
Anyone out there try the throttle bodies on a 850 with SLP single and SLP head? Any real world feed back?
You will probably get some feed back this weekend.
