XP big bores - lets compare

[Fack]

In a forced air induction system by raising the intake and lowering the exhaust it gives you an opportunity to increase cylinder pressure by decreasing the amount of air/fuel mixture that escapes out the the exhaust. Also, in a forced air situation you create a longer more consistant burn and with the lower exhaust port you are able to utilize that energy longer before it escapes out the exhaust port. By doing this you add significant torque to the low end and you are able to transfer in and out of boost more affectively. I would absolutely support the idea of a turbo specific ramp as well. The TRA concept is great in the sense that you can change how the clutch loads the motor by more than just adding weight. It adds a new dimension to tuning that helps with the non-linear power curve that a turbo creates. There are obviously some quality and durablity issues involved with the TRA but I don't think there will be any issues on an XP if set up properly. That's how I've come to understand things anyway.

-Fack

 

[Original Tetonice]

In a forced air induction system by raising the intake and lowering the exhaust it gives you an opportunity to increase cylinder pressure by decreasing the amount of air/fuel mixture that escapes out the the exhaust. Also, in a forced air situation you create a longer more consistant burn and with the lower exhaust port you are able to utilize that energy longer before it escapes out the exhaust port. By doing this you add significant torque to the low end and you are able to transfer in and out of boost more affectively. I would absolutely support the idea of a turbo specific ramp as well. The TRA concept is great in the sense that you can change how the clutch loads the motor by more than just adding weight. It adds a new dimension to tuning that helps with the non-linear power curve that a turbo creates. There are obviously some quality and durablity issues involved with the TRA but I don't think there will be any issues on an XP if set up properly. That's how I've come to understand things anyway.

-Fack

Fack that all sounds rosey in theory and we all understand the process thats done which in the end will still result in minimal hp gains. Furthermore in carberated sleds such as the XP (non-efi) the ambient operating temps play a huge factor in how the air/fuel mixture burns during sled operation.

I don't know what your trying to say in regards to transfering in and out of boost more effectively Are you refering to lag ??? When the XP, Polaris or Cat 800's are tuned well NO LAG or transfer of power in and out of the boost is occuring. The power curve is crips and clean fromm the bottom end through the top end. I've Sqweezed Plenty Of Turbo's to Know !!!!.

As for the TRA it's already Tunable and perhaps even allows more fleaxability for turbo's than any other clutch...Did I Say That ? Thats A Stretch ... There are also plenty of tunable cutch kits available Heavy Hitters and Super Torquer come to mind, heck theres even an adjustable helix that's ideal for turbo applications.

Back to my question....Will "ALL THE EXPERTS" explain where the 17HP gain is acheived by just porting/head only ?

Are You Running 100% Race Gas ? I Sure Hope So

OT

 

[gus bohne]

Fack
the tra is just about useless for a turbo on anything but snow.

We cannot use them on asphalt or ice as they have a severe issue with full shift belt squeeze AND low end belt grip.

Its something we just are wasteing effort trying to get around. You'll find more people making race winning passes on ice or asphalt using a fixed roller rather than a fixed ramp.

Port timing, area and angle of entry as well as head design are very big players in either boosted or non boosted applications.

The gains can be very very impressive.
Just compare your stock sled vs JUST porting and head with proper pipes.

I.E. the 800 triples, 155-165 stock 800cc

Imp stock same engines are over 220 hp, so the gain is VERY impressive .

transition onto the pipe and its respective effect on engine pumping and power output can be tuned with lower ex port timing, but be carefull of loss of effective blowdown area as well as time.

One can easily get the ex port into a position of great torque below the pipe window, but be in deep sheet when its at full song !!

takes a lot of testing and time spent evaluating the gains and losses to find the best overall package for your intended END USE ..

done right a properly port itmed and headed turbo 2 stroke will see gains over 20% ,, thats actually really easy, its getting over that 30% hurdle we are now trying to jump !

hope this helps get you where you want to go.


Gus

 

[winter brew]

Gus, unfortunatly....real life testing and results have no influence in OT land.

 

[Original Tetonice]

Mods do this, Mods do that... everyone spouts off about what there mod can do...However rarely does it come close.

Simple questions folks ......Since porting a 2 stroke engine can only gain 4 to 6 HP at best where's is the additional HP coming from ?? The HEAD !!!

Gus Bohne pipes do add HP now you want to add a pipe ? Single or Twins ? Shoud we add Reeds to clean up throttle response as well ?

You guy's must be smoking some good stuff in the backroom or just making up hp numbers as you see fit. Or Both LOL


OT

 

[DWHalverson]

I was just jokeing.

Dave

This big bore post sure went to hell with all this "TurboTalk". I'll throw some info out of the bag. With all of the extensive dyno runs on our turboed XP kits in stock trim and the turbo vs the same kit with turbo specific cylinders and turbo specific head we gained an additional 17.3hp @ 10psi.








Our turbo ground ramps only gained 1.2hp. This was a huge dissapiontment. I thought there would have been more power in the turbo ramps .

Have a good day .

Dave Halverson

 

[BIG JOHN]

gus, unfortunatly....real life testing and results have no influence in ot land.

x2...bj

 

[Original Tetonice]

Heres a real lfe test ..... I find it kinda funny that none of the self proclaimed mod engine guys can answer how its possible to gain 17 plus HP from Turbo Porting/Turbo Head.

OT

 

[DWHalverson]

OT I think Gus and Fack did a good job of explaining how the gains "could" be achieved. Like I said in my earlier post, I was just joking . I have never had one on the dyno. For the turbo ported cylinders and head at this time I need to stay focused on the "consumer" kits. The turbo specifc heads and cylinders make more power, but I still have to finalize the consumer kits. The upgraded hot rodded versions will come later after I can test those. I will not sell anything I have not tryied personally. Sorry if you got caught up in my numbers BS, but it was all in fun.

Dave

Heres a real lfe test ..... I find it kinda funny that none of the self proclaimed mod engine guys can answer how its possible to gain 17 plus HP from Turbo Porting/Turbo Head.

OT

 

[BIG JOHN]

Heres a real lfe test ..... I find it kinda funny that none of the self proclaimed mod engine guys can answer how its possible to gain 17 plus HP from Turbo Porting/Turbo Head.

OT

LOL...its there...ripe on the tree...within reach...I cant resist...I have to...aaaaugh!!

One would think a blow hard like you would know the benefits of a turbo...LMFAO-BJ

 

[tntm7]

power gains with porting on a turbo

I have seen porting loose as much as 40hp on a turbo motor.
You ask how 17hp gain on turbo two stroke is possible, thats pretty simple, no turbo motor that I know of likes high blowdown timing, the 800r has high port timing, raising the transfers and lowering the blowdown timing will increase trapping time, and keep the boost in the cylinder, 17hp, I think is a very low number for 10psi, think there is more, just going to take more then a 140deg transfer to find it.
OT, on a 2007 m8 15hp is easy to get from porting and a head mod.
800r motor, different story.

 

[mark4]

Terra Alps makes a strong 860, works well with jaws twins, tested at elevation with greg while making them.

 

[BIG JOHN]

SHR860R "Holeshot"

The Cat in the next lane over is a M8 w/900 BB @ twin pipes....the Rev was a twin pipe "MOD racer" ...and there is a sled in the near lane (another CAT), just kinda left it for dead...there was about 2 sled lead at the finnish...BJ

 

[Original Tetonice]

BJ everyone knows that Cats are slow out of the hole....I can't help but notice how the Cat rear suspension appears to be collapsed when comparing it to the XP.

Line up against a Polaris next time BJ.

OT

 

[BIG JOHN]

BJ everyone knows that Cats are slow out of the hole....I can't help but notice how the Cat rear suspension appears to be collapsed when comparing it to the XP.

Line up against a Polaris next time BJ.

OT

So adding to the "holeshot" and "winning by 2 sleds" means???

Polaris what?? I have raced plenty O'Polaris...not worried...

As for the Cats skid, those sleds showed up "lowered" for rac'n...BJ

 

[Insaneboltrounder/sjohns]

OMG... does the BS tap at OTs house ever shut off? The smell must be unreal. "Everyone knows cats are slow out of the hole" ...Really ??? Seems they did pretty well in snocross.
The only thing everyone knows for sure is that OT is a complete azz and knows dickall about anything related to sleds or snow.

Go to page 15 of this thread to see a pic of the master of Bullsheet , mastering a mountian. sj

 

[NoSecondChances]

OMG... does the BS tap at OTs house ever shut off? The smell must be unreal. "Everyone knows cats are slow out of the hole" ...Really ??? Seems they did pretty well in snocross.
The only thing everyone knows for sure is that OT is a complete azz and knows dickall about anything related to sleds or snow.

Go to page 15 of this thread to see a pic of the master of Bullsheet , mastering a mountian. sj

If you're slow out of the hole.........aren't you part of the problem?

 

[Insaneboltrounder/sjohns]

Only if you dont counter steer or try to make your tra ramps move

 

[Reese]

Old OT performance secret....

If those cats would have done thier engine breakin on a track stand they would have been waaay quicker out of the hole.

 

[Dynamo^Joe]

OMG... does the BS tap at OTs house ever shut off? The smell must be unreal. "Everyone knows cats are slow out of the hole" ...Really ??? Seems they did pretty well in snocross.
The only thing everyone knows for sure is that OT is a complete azz and knows dickall about anything related to sleds or snow.

Go to page 15 of this thread to see a pic of the master of Bullsheet , mastering a mountian. sj

never mind, i'll repost it.