🔧 BUILD Upside-down M90 GTP build thread

[sktchy]

That kind timing I'd throw all the boost at it

 

[Turbocharged400sbc]

I think maybe you're just looking at your rotors having worn into the case after it's relocation upside down. I wonder if you slapped new rotors in there whether you would gain that boost back till they wore back down.

I know our blower case shifted after I cut off the inlet.
I ended up grinding the tops of the bores after we welded on the new plenum but I think that's partially because the weld was less than half an inch away from the rotor surface along the top edge of our new throttle body plenum.

Put a methanol nozzle in the middle of that giant gaping hole that you've been shoving your pecker into and see if that will tighten up the clearances and gain you back the Boost?
You can probably do something fairly effective with just a long vacuum hose and a mouth full of water while you're driving

 

[Mr_Roboto]

I think maybe you're just looking at your rotors having worn into the case after it's relocation upside down. I wonder if you slapped new rotors in there whether you would gain that boost back till they wore back down.

I know our blower case shifted after I cut off the inlet.
I ended up grinding the tops of the bores after we welded on the new plenum but I think that's partially because the weld was less than half an inch away from the rotor surface along the top edge of our new throttle body plenum.

Put a methanol nozzle in the middle of that giant gaping hole that you've been shoving your pecker into and see if that will tighten up the clearances and gain you back the Boost?
You can probably do something fairly effective with just a long vacuum hose and a mouth full of water while you're driving

The question in my mind is could you do something like dykem or sharpie or hell even use some gear marking paste and check the mesh/case fitment? I realize it may be a pain in the jimmy but figure I'd ask. How would a company that does roots like Heaton, Dyers, GMC etc. have done it/does do it? Ultimately they have to.

 

[Turbocharged400sbc]

There's always clearances intolerances with something that expands as it heats up. But that's why all the serious blowers use teflon strips on the rotor lobes to seal them

 

[Mr_Roboto]

Very true but at the same time if there's say an asymmetry in the case it will wear in a way that probably won't seal well fairly quickly.

Does anyone make over sized rotors for case rebuilds? That'd be my thought, get the case re-trued and oversized rotors if so.

 

[GTPpower]

I guess I should buy a water meth kit and try that. Maybe the 1/2" aluminum plate that holds it, isn't as strong as I think it is.

Anyone know if it's possible for belt slip to still show fairly consistent boost? When I ran a 2.3, it was super obvious when the belt would slip, but on the 2.7 and 2.8 boost stays pretty consistent. I was thinking about going to an 8 rib.

 

[v6buicks]

With pullies that small I'd be surprised if 2 extra ribs were enough. Replace the snout with an overdrive transmission. lol

 

[Turbocharged400sbc]

Crap you're on a six rib still?

Toss on a brand new belt and run a triangular file hard through the grooves to put some teeth on your pulley

 

[sktchy]

Somethin Somethin just stick a hose off the washer tank behind the maf or whatever

 

[GTPpower]

I have a npt port in the throttle body spacer for future meth injection, but remember that's post blower. To inject water/meth into the blower, it will end up going through the intercooler, TB, and maf. I wouldn't mind trying a little water in it, but not sure I want to do too much.

I've never run anything more than a 6 rib on any of my cars. I never really saw much of an advantage to more belt surface since it results in less pressure. But these pulleys are cheap. I should try the triangle file trick and see what happens.

 

[Turbocharged400sbc]

Have you looked for debris in The Valleys of the belt? Run a sharp pic across there and you'll probably see tons of little Stone and glass Pebbles

 

[Turbocharged400sbc]

That debris doesn't let the belt ride fully down in the grooves and then apply pressure to the V

 

[GTPpower]

I have not. I'll take a look and see.

 

[GTPpower]

Getting my winter updates inline for the car. These showed up the other day.



Should I switch cams? Or stick with the xpz?

 

[sktchy]

You go with whatever cam you think is right ? if you decide to twin charge it I'll make you a screaming deal on this is4 turbo cam

 

[Mr_Roboto]

For a blower I'd run that. I'd think good things would happen.

 

[GTPpower]

For a blower I'd run that. I'd think good things would happen.

The is4 turbo cam? Or the xpz?

 

[Mr_Roboto]

I wouldn't do their turbo cams they look to be reverse pattern. You're running a blower still you want extra exhaust duration even though the 3800 head seems very efficient based off flow #s. How much street use will this see, how much stall are you willing to run, and how high are you willing to spin it? Those are the questions in my mind for the cam selection. Being soft on the bottom end may not be the end of the world in a FWD car quite honestly. May actually help you keep some parts in it to do what would normally be over camming.

Assuming racey I'd go for the IS3 or IS4 supercharged cam or even the IS3 N/A cam. If you're not willing to spin it super high I'd try what you have. The big thing in my opinion is the easier air flows through the engine the more the Heaton can give you. The XPZ is a huge step up from the stocker though and I don't know that I'd be afraid to leave it until I squeezed everything from it.

 

[GTPpower]

Ok, I will just stick with the xpz then. I know it has more in it.

It basically sees no street use. I don't really care much about drivability. I have a 2500 stall on it. I could go higher, but I have doubts it would help the car go any faster. As for rpm, 6500 is about as high as I feel comfortable.

 

[GTPpower]

I'm going to throw this gen 3 on and see what happens. Anyone have the 8 rib pulley part numbers?

 

[Turbocharged400sbc]

I want to say you just look up idlers for Ford and GM diesels

 

[GTPpower]

 

[Mr_Roboto]

 

[sktchy]

Are you gonna flip that one upside down too?

 

[Turbocharged400sbc]

Meh.

By the way unless that's the core that prj modified for a post-core boost bypass passage for the external boost bypass valve.

delete the Boost bypass valve if it does not pass through the intercooler core before getting recirculated back into the blower.


The animal kit does that and it's a s***** compromise.
it's what led to lunching the Whipple on The WhippledRiv