Re: What size Wastegate? For ATV
 

i personally think your not making boost until 4k rpm is because your header is to long
there is a reason all those turbo busa's and basicly anything turbo they are mounted as close to exhaust ports as possible it's because that is where the exhaust gasses are at their highest velocity i say move the turbo up in front of the engine, and build a shorter header and that will help you build boost also it should help with cooling a bit aswell (sorta like ram air at speed, and the radiator already has a fan on it to pull air though and twards the eninge that should also help keep it cool)
and then you would be able to throw a small air-air ic where the turbo is now with a couple scoops to catch air and you would have plenty more cooling for safer boosting and could build boost sooner tho i am not promising that your turbo is to small because it verry well may be
you said that it starts making boost at 4k rpm but never said where the boost levels off at or if it does or at what rpm

Re: What size Wastegate? For ATV
 

what about the fact it's a 700cc enigne pushing a gt28

Re: What size Wastegate? For ATV
 

+1 the long tubes will make it spool a little slower but the main problem is to large of a turbo imo ;)

Re: What size Wastegate? For ATV
 

Get a Mitsubishi TC03 - they used them on the 650cc Seca... should be alright on a 700. Two-bolt flange, too. Easy to fab. :y

Re: What size Wastegate? For ATV
 

I know the turbo's off of passat's are tiny maybe small enough for your application?? i know its smaller then the gt28

Re: What size Wastegate? For ATV
 

ko3 peanut

Re: What size Wastegate? For ATV
 

On this setup, on the dyno, anything smaller than a gt20 it started loosing power across the board. The only reason why I'm running the Gt28 is because it was the only ball bearing turbo that I had available, without having to shell out for a gt25, which I might do in the future.

Alot of the bushing, lubed turbos in these kind of applications seem to not last long, or so other Turbo'd atvers have told me, with all the sand, all the different loads of climbing hills, puts alot of stress on everything, let alone the turbo.

And there are two reason why the turbo is back there like it is. The number one reason being, this cylinder head has two exhaust ports exiting the head, facing away from each other at about 45*, it is pretty difficult to get a header to line up to a single collector, and fit it under the frame right there. I wish I could do that, that would give me the ability to run an intercooler. And the Second reason for running it back there..... it is ALOT more sneakier >:D At first glance it just looks like it has a different silencer on it (this is the stock header with heat shield). And now the way I have it hidden makes it quite difficult to see the turbo.

I do agree with all of those reasons of slow spooling, being the long header and large turbo.... this particular bike has a 102mm bore and 96mm stroke..... so there is alot of room in the combustion chamber to make havoc.

And the third reason why I'm leaving this turbo.... this bike will soon be a 907cc stroker, that is .907 liters lol

I wanted to get this wastegate situation worked out, but thanks to you guys now I am going to try a MBC, and see what the results are. Within the next month this bike will be on the dyno, to fine tune the AFR, and to see how capable it is with another nitrous set up I have.

After the 907 stroker, more boost (Still workin on it) I am projecting somewhere around 150hp to the wheels, and will be addiing a 50shot on top of that. I am very conservative and safe right now, but soon this thing's gonna haul ass or blow, and if it gives I had fun doing it, no problem with me ;D

Tony

Re: What size Wastegate? For ATV
 

If you are going to add a MBC then i would definitely run another vacuum line just for the BOV. If not that then at very least T off the current vac line before the MBC

Re: What size Wastegate? For ATV
 

I have a vacuum line running off my wastegate now going to my BOV, what purpose does this serve?

Re: What size Wastegate? For ATV
 

I personally think you're the biggest tard I've ever seen in the history of this website.

The gas does not have it's highest velocity at exit of the engine, this is where it is most turbulant point, the enthalpy would be the highest in the exhaust stream (which is why short log mani's spool quicker, there's a higher pressure differential) but velocity is an acceleration, which in a fluid is a flow.

The only thing you could argue about would be the amount of time it takes to fill the extra volume the longer tubes creates, which doesn't matter anyway because that area is pressurized just about from 1k rpm and up.

Too big of a turbo would cause lag like this man experiences.

Ass sandwich.