Author Topic: APT 40mm Billet Smart Carb mounted on a 431 Puma. With important mounting notes. (Read 45916 times)

toydoc · « **Reply #60 on:** November 23, 2014, 07:27:47 AM »

Quote from: udontknowme;46315

thats not bad, all things considered, and with the new technology theyre using. i have a idea for a twin cylinder engine totalling 500cc. if it ever makes it to fruition i estimate about 4.5 hp per CI or .28 per cc, using gas and a standard keihin or mukini style carb and no fancy electronics of any kind. seems like the size of your wallet is always the determing factor :highly_amused:

Quote from: Jerry Hall;46320

Snowmobile engines do not usually have their power over as wide of an RPM range as engines with transmissions. It is a lot easier to make huge peak power numbers if you do not need it over a wide RPM range. The CVT can hold the engine at it's peak power.

I'll side track the topic a bit, sorry. All of my Mod sled motors make peak HP over 500+ rpm sweep just like mod ATV motors. Plus they are .30 hp per cc. A CVT can't just start at peak HP. Most start at 4500 ~ 5000 RPM then end at 9800 ~ 10,000 RPM. To tune a CVT and WIN takes alot more work then you think. I wouldn't use the word easier in any part of it. Your 60' time is everything and if your waiting to make power, you wont win. IMO it takes running 1.1's in 60' and a peaky motor wont turn that time

rsss396 · « **Reply #61 on:** November 23, 2014, 08:59:08 AM »

Quote from: SmartCarb;

46351 Wobbley has been building SC equipped GP twin 2t race engines in New Zealand/Australia for years and we have one in our pikes peak quad.

It's strange that you did mention wobbly, because I have only seen him mention the smart carb once and it was in reference to the pikes peak
Quad but he stated that he quit helping with development of it when his request for a adjustable power jet were ignored.

rsss396 · « **Reply #62 on:** November 23, 2014, 09:36:06 AM »

I will say I do like the oviform shape of the SmartCarb and also the old PSI BigAir carb, this should work especially well at smaller throttle openings and never understood why the other carb manufacturers did not use it.

SmartCarb · « **Reply #63 on:** November 23, 2014, 09:53:43 AM »

Quote from: toydoc;46457

I'll side track the topic a bit, sorry. All of my Mod sled motors make peak HP over 500+ rpm sweep just like mod ATV motors. Plus they are .30 hp per cc. A CVT can't just start at peak HP. Most start at 4500 ~ 5000 RPM then end at 9800 ~ 10,000 RPM. To tune a CVT and WIN takes alot more work then you think. I wouldn't use the word easier in any part of it. Your 60' time is everything and if your waiting to make power, you wont win. IMO it takes running 1.1's in 60' and a peaky motor wont turn that time

Well said. Most find stock to reasonably ported exhaust and longish tuners the answer for clutching nightmares in drag racing. Ski-Doo's TRA clutches also really help to compound torque out of the hole and has answered a lot of problems in stock class racing. Conversely, Polaris and Arctic Cat have the luxury of a compound overdrive but take a lot more finesse to beat a rotax in 660ft. But you'll see them gaining mid track every time. We were desperate enough to keep from pulling the belt in half on our 340 and 440 sno pro rotax's back in the day we made a slipper clutch for the jackshaft so we could leave the line with the clutches and belt already engaged. 6800-12,500 rpm. Worked pretty good until one came apart and did a number on my left foot, finally relented and added 7/8" to the head pipes and 145 deg. rotary plates. Sad though if you've ever heard one at full song, they never sounded the same after that, but were much quicker in 60ft times.

SmartCarb · « **Reply #64 on:** November 23, 2014, 10:14:58 AM »

Quote from: rsss396;46458

It's strange that you did mention wobbly, because I have only seen him mention the smart carb once and it was in reference to the pikes peak
Quad but he stated that he quit helping with development of it when his request for a adjustable power jet were ignored.

Except Rob Berrington-Smith has been racing with them for two seasons http://m.youtube.com/watch?v=7Ve2Y86dP7U

Jeram on twostrokemotocross forum posted this recently http://twostrokemotocross.com/forum/technical/apt-smart-carb/

Quote

I spoke to Wobbly (Honda NSR500 GP technicial) back in late January.

He had tested the billet SmartCarbs and he said he thinks theyre unreal.

To be clear. Wobbly was not, has not, been helping with the development of the SC, and as far as I have spoken with him, he has never requested a power-jet. We have sent him different metering rods to try over time. Perhaps if you could reference where you heard that would be interesting to know. He built the pipes for the quad in the picture and advised Wilson Performance on the Cheetah cylinders. I sold him the 40's off the quad and a 28mm for his bucket 50cc. The 40s have been running on Wobbly's RZ400 ridden by Rob Berrington-Smith. Wobbly would like to be our distributor down under and I think his only problem with the SmartCarb is getting his hands on as many as he can.

SmartCarb · « **Reply #65 on:** November 23, 2014, 10:43:18 AM »

Quote from: rsss396;46460

I will say I do like the oviform shape of the SmartCarb and also the old PSI BigAir carb, this should work especially well at smaller throttle openings and never understood why the other carb manufacturers did not use it.

Kawasaki used a keyhole shaped carb back in the 70s and there have been several variations over the years. Lots of aftermarketeers have offered offset bore carburetors. Today we have this shape patented and the predictive technique used to design it. PSI actually was infringing on our patents a year after they saw an SC at the hillclimb in Jackson. So as gentlemen we offered Bruce Kahlhammer a licensing arrangement to continue selling the V shaped venturi they had started using, (not the early D shaped big air they have patents for) however after some rude discourse we ultimately had to serve them with a cease and desist order. Turns out the design they had didn't work all that well and they weren't selling enough to really matter. You'll note they had large scallops cut into the venturi to diminish laminar flow and frankly were going in the wrong direction. I'm not sure they are even still in business, which is too bad, they had some pretty cool stuff at one time.

rsss396 · « **Reply #66 on:** November 23, 2014, 11:40:06 AM »

Wobbly posts on many forums but the forum I refrenced from is a private engine builder forum. I will try to gather his latest thoughts since this was made in August 2014

SmartCarb · « **Reply #67 on:** November 23, 2014, 01:41:49 PM »

Quote from: rsss396;46474

Wobbly posts on many forums but the forum I refrenced from is a private engine builder forum. I will try to gather his latest thoughts since this was made in August 2014

I'll call him. Appreciate your making reference to it and interested to see what he was thinking.

rsss396 · « **Reply #68 on:** November 23, 2014, 02:37:12 PM »

Wobbly's a sharp guy and hard headed, it would not surprise me if he did not drill yor carb and put a power jet in it.
He use the same trick some of the factories use by switching off the electric power jet in the overrev to build heat in the pipe for more rpms

SmartCarb · « **Reply #69 on:** November 23, 2014, 02:50:42 PM »

Quote from: rsss396;46481

Wobbly's a sharp guy and hard headed, it would not surprise me if he did not drill yor carb and put a power jet in it.
He use the same trick some of the factories use by switching off the electric power jet in the overrev to build heat in the pipe for more rpms

Oh for sure, he's pissed at me because I couldn't deliver a bunch of carbs to him. I made reference to TSS and the experience was similar and holy hell the romance was over. So he may have out of spite. Ha! No he's brilliant, but I'm thinking he's not the first if he's tried. Had a couple blokes from New South Wales call in to order a bunch of new parts for 3 billet 38s they had fixed....

Hawaiiysr · « **Reply #70 on:** November 23, 2014, 03:01:57 PM »

Fixed, haha!

rsss396 · « **Reply #71 on:** November 23, 2014, 03:28:06 PM »

Haha yeah don't bring up the TSS word lol

Jerry Hall · « **Reply #72 on:** November 23, 2014, 05:32:50 PM »

Quote from: toydoc;46457

I'll side track the topic a bit, sorry. All of my Mod sled motors make peak HP over 500+ rpm sweep just like mod ATV motors. Plus they are .30 hp per cc. A CVT can't just start at peak HP. Most start at 4500 ~ 5000 RPM then end at 9800 ~ 10,000 RPM. To tune a CVT and WIN takes alot more work then you think. I wouldn't use the word easier in any part of it. Your 60' time is everything and if your waiting to make power, you wont win. IMO it takes running 1.1's in 60' and a peaky motor wont turn that time

The smartest guy on a sled team is often the clutch guy. :stung: or should I say if he gets the set up right he can be the hero or if he gets the set up wrong the whole team is a zero

In any winning effort it takes the best of the best of everything. Best rider, best engine guy, best clutch guy and best chassis guy.

The point I was attempting to make in an earlier post was: A CVT has more ability to keep an engine close to the power peak while a package with a multi-gear transmission must have a high power average over the RPM range that the transmission ratios define. To get equal acceleration for two vehicles of equal weight the CVT can do it with a narrower spread of power than the other vehicle with a manual transmission. I takes a less effort for me to develope a two stroke engine package with a power peak that spans 500 RPM than it does to build an engine package that has a peak span greater than 500 RPM.

SmartCarb · « **Reply #73 on:** November 23, 2014, 05:49:40 PM »

Quote from: rsss396;46484

Haha yeah don't bring up the TSS word lol

Well it's all about suppliers right? Same BS we go through every day, we can do your work-meet your tolerances etc. End of the day...no.

toydoc · « **Reply #74 on:** November 26, 2014, 06:08:38 AM »

Quote from: SmartCarb;46467

Kawasaki used a keyhole shaped carb back in the 70s and there have been several variations over the years. Lots of aftermarketeers have offered offset bore carburetors. Today we have this shape patented and the predictive technique used to design it. PSI actually was infringing on our patents a year after they saw an SC at the hillclimb in Jackson. So as gentlemen we offered Bruce Kahlhammer a licensing arrangement to continue selling the V shaped venturi they had started using, (not the early D shaped big air they have patents for) however after some rude discourse we ultimately had to serve them with a cease and desist order. Turns out the design they had didn't work all that well and they weren't selling enough to really matter. You'll note they had large scallops cut into the venturi to diminish laminar flow and frankly were going in the wrong direction. I'm not sure they are even still in business, which is too bad, they had some pretty cool stuff at one time.

Bruce did spin out back then. Went through a divorce, then a group remade Scorpion brand snowmobiles and ordered ALL the production motors from Bruce and didn't pay or went belly up. Sad deal. Last I knew he out in Utah playing with mountain sled heads.

Odd thing about patents, they don't stop anyone from using it. It just gives you the right to take them to court and fight