Speedwerx DryPipe - Any Good?

[MADMAT]

OTAY. Thanks to BK I notched mine out last year and that solved the coupler problem. The mount you can't see on the flywheel cover did'nt need anything done to it.

I just put the pipe in place and decided where to notch on the top 2. I can't even imagine someone not running a strainer on this pipe! I think a friggin paramecium could clog this pipe!

Also I cut the hightempsilicone.com couple at an angle because the rear hose clamp tends to want to slide back on the bottom. The top is fine because it hits the curve in da pipe. I may even weld a small aluminum block onto the bottom of the pipe to help keep the damn clamp in place if this does'nt work.

I gotta say though that even though I had one miserable summer learning what to do to this pipe...I LOVE IT. It is sick!

I'm running highly ported cases with 81.5 62t cylinders and no porting. I have ridden a lot of skis with B Pipes and ported cylinders and mine hits just as hard if not harder in some RPM's.

Also my chamber comes out very easily. I can have it out in 10 minutes.

FYI: I am only at 155PSI and I run 94 octane. I can't imagine what it would do under superstock conditions!!

Also, I rarely do WOT for more than a minute or so.

 

[Big Kahuna]

Stock701 Cylinder. I believe it's a 61X it's on a 2000 SJ

The detonation issues are not a factor on a stock set of cylinders........ In fact, if I was to build a Dry Piped Limited, I would use a Speedwerx Pipe.............. The Deto is more of an issue with higher horsepower engines (IE Ported) than non ported..........

I did not have to mod my hull......... you do with the Type 4 Dry pipes (at least on sum hulls, clearance issues.)

 

[Matt_E]

In my hull, it was absolutely necessary to cut about 1/2 inch from the lip. Couldn't get the chamber out without that.
Is there really that much variation in SJ hulls to where you didn't have to do that?

 

[MADMAT]

I don't know about the variation but maybe someone cut this hull before I got it. It does'nt look like it though.

Mine just moves back and up and out.:dunno:

 

[Matt_E]

Good for you. There was no way to do that on my hull.

 

[93SJ760]

Xjetrider,

I'm running domed pistons. I believe my bore right now is at 85.5mm if I remember right. I couldn't tell you my dome size as they are in a Riva girdled head and read 31cc, 81mm but the head has the o-ring grooves milled out of it to be used with gaskets and the domes were cut custom, set-up for pump-gas with 0.045" squish and 185psi.

I plan on cc'ing the domes but need to buy some hardware to be able to do that.
Tyler

 

[Matt_E]

Holy cow...if you're at 85.5mm bore and you're running 185 psi, yeah, you'd have deto.
Even without a dry pipe.

 

[93SJ760]

On my gauge (Which I think reads a little low) I have 180/185 psi. I've run this motor for a few hours now without an issue and when I took it apart the domes look clean. No signs of deto.

I hope this isn't the case? The guy who helped me set it up really seemed to know what he was talking about. The only thing he mentioned was to not run a Riva CDI as they're bad for deto.

 

[Matt_E]

If you are really on an 85.5 mm bore - and if you got a 61x cylinder, that means you run big bore sleeves (custom) - then 185psi is deto land on pump gas.

 

[93SJ760]

Matt E,

I just went to the garage to check out the cylinders to see if they were 61X and they don't have the model stamped onto them where I can see. (I thought they put it on the top of the boss for the exhaust port). I am pretty sure that the guy re-sleeved as the 701 sleeves weren't thick enough. Just not sure if he built them out of 61X or 62T cylinders.

I should learn more about my ski. I'm feeling like an idiot right now.

 

[Matt_E]

If you can bolt a Speedwerx manifold to it, it's probably a 61x cylinder. (The exhaust bolt holes in a 62T are larger)
Are there timecerts in those holes, perhaps?

Measure the bore. Measure the domes. Be sure! You don't want that deto'ing again.

 

[Big Kahuna]

Just because he is at 85.5 does not mean he is at detonation stages...............

I am running 83mm at 200 LBS at Sealevel......... guess what, no detonation............ It is all in your port timing, squish and timing........

 

[Matt_E]

Harrison, I am convinced that 85.5 at 185 lbs is deto land. Know what stock compression for a 760 (84.00) is? There's a reason for that.
The bigger the bore, the sooner you get into higher octane fuel for comparable compression levels

83.00 is no where near 85.5

 

[Big Kahuna]

Porting, Timing and squish is your biggest factors with Deto..........

I am running 195 lbs with no deto.............. 92 octane

That why you pump gas porting and race gas porting...........

 

[Matt_E]

I agree....but bore has a lot to do with as well. And it is a fact that with larger bores, you need to run less compression to stay pump gas safe.

 

[ArtMaybee]

hmmm... That's the first time I've ever heard anything like that.

If that's the case, why is 180lbs still the max recommended for a 440 which has MUCH smaller bore sizes than we are talking about here. With that logic, a 440 would be able to run higher PSI compression safely than a 701, 760 etc.

I know people who have run between 180 and 195 on 84 and 84.5mm bores with NO problems using pump gas. One friend ran 200lbs on a 701 with pump gas for years and no babying the throttle. This boat never had issues either.

It would be very hard to make a broad statement like..... " if you're at 85.5mm bore and you're running 185 psi, yeah, you'd have deto.
Even without a dry pipe."

Because even seemingly identical engines can vary WIDELY in how different setup changes can effect them. Things that work for one person can totally grenade somebody else's. There are things that seem to work for people the majority of the time and that's what people usually advise here.

 

[Matt_E]

How about" IMHO, I find it very likely detonation would occur on 185psi @ 85.5mm."

 

[FL-cracker]

^^^^ So what is safe compression for pump gas? Id like to know as well. I am putting together a

85.5 flat tops TLR freestyle ported cyl.
dual 46 red tops
limited B-pipe /B1
All stock ignition, I was going to get an Msd enhancer soon. Now im not sure what I will do, I realy dont have $1200 for total loss.

It is a Greater yamaha head with flat top domes and reg domes. I was going to try a waveraider head gasket with the flat top domes, and see where the compression is. Then I thought why couldnt I just use the regular domes for domed pistons, as there are more cc's. Not sure what size either set of domes are. Has anyone ever ran flat tops with reg domes?

I guess I will be doing alot of playing, finding where my compression will be.

Sorry, not trying to thread jack

Thanks

Bronson

 

[Matt_E]

I won't throw out a number. You may be fine with pumpgass on 185psi if you aren't doing WOT runs. Maybe not.
I'd be careful. Contact one of the pro-engine builders that frequent the site and ask them the question. They would be much more qualified to anwer that.

 

[SuperJETT]

170psi with 10 degrees advanced timing will detonate you. 240psi with stock timing will too. You have to find a safe point for each engine, but typically 180psi is an unwritten limit.

Also, cranking compression is not an indication of being pump gas safe because the squish clearance/angle/area plays a huge part in the equation as does the pipe and rpms and everything else.