FGT supercharger swap project

matt270avian wrote:

Pretty sure we can weld aluminum, but I would have to ask my friend if he still has the gas for it. Shoot it on up here if you want.

Don't you have to use a TIG welder for aluminum? Or is there something I'm missing that allows you to use a MIG welder for aluminum?

You can use a MIG, all you have to do is lower the voltage a bit, use a thicker wire, and a different gas. It won't be as pretty as TIG welds but it gets the job done.

I basically finished the throttle body plate so the intake thingy is as good as done. Hopefully I don't have any unforeseen problems with it.


There's some of my working sketch. Designing this stuff is always a mixture of fun and aggravating. Everything about this was quite deliberate. The 5-bolt pattern is for connecting the throttle body plate to the tube that's pictured above. The hidden (dashed lines) are where the seal sits around the opening. Five screws is the most I can have evenly spaced without interfering with the throttle body's seal where it goes down to box off the IAC passage. The tube will have that five-bolt pattern four more times around so that I can actually clock the throttle body twenty different ways to help with clearance and throttle cable arrangement and whatnot. That "0.4375" hole I added last minute for an optional PCV inlet entry. It's tapped for 1/4NPT.

I love it!  How close will this put you to making more boost than the engine can handle?  Or more power than the fwd suspension can handle?  Has anyone tore a motor out of the mounts yet?

You know I love the Riv but - why a Riv?  I can understand the simpler, cheaper mods, but you're getting into the madness.

did that last little transition angle real quick and sand blasted it. Now I gotta find some paint that matches the bright silver powdercoat on the blower and make it look stock.


There's the northstar throttle body seal laid on top for general reference.

Jack the R wrote:

I love it!  How close will this put you to making more boost than the engine can handle?  Or more power than the fwd suspension can handle?  Has anyone tore a motor out of the mounts yet?

You know I love the Riv but - why a Riv?  I can understand the simpler, cheaper mods, but you're getting into the madness.

More boost than the engine can handle is practically impossible with this blower IMO. It is designed to work to about 20psi and more than that is very doable but it'd be drawing easily over 150hp from the crank at that point and i'd never get the serpentine belt to hold on over that. It's gonna be fun to see what limits I run into with stuff but I don't think at all the block can't take the boost - could definitely lift the heads if timing gets too hot but really it's gonna be a blower/drive issue first.
As a side note, this will be working on an L67 (low compression) block, not the L26 in my sig - I'll be swapping that in the next few weeks if it goes according to plan. On paper, my built trans should be able to handle anything I'd dish out even with this blower. If I can make 450-500 at the tires, I'll will be foaming from all pores with joy.

I haven't heard of tearing out motors mounts. I've heard of a couple cases of people fracturing transmission housings which would really suck.

Despite it's many practical shortcomings as it gets older, the riv is my favorite car period. Every time I visit getting another car to play with, it comes down to missing some big component I love about the riv. Sometimes it's just the nebulous factor of the riv that other cars lack, not to be mistaken with sentimental value. The available low-cost engine just helps me justify doing what I want to do with it. The riv sticks with me but I think I'd be doing the same kind of thing if I had a different car - it's just my way.

It's great to see your enthusiasm for such an obscure car. I got to talking to a couple guys on Deviant Art about it. One had an 8th gen Riv and traded it for, ah, I don't think it was a Marauder but some version of Grand Marquis with more performance? The other guy considered the Riv one of the top 5 ugliest cars ever. I don't see it I love the way the Riv looks.

Refresh my memory, the stock supercharger only makes around 6 psi of boost, right? How much can the motor take? How much do you expect tog et with the FGT supercharger?

6-8 PSI of boost on a stock supercharger depending on the weather.

i've read max efficiency of M90 is 9-11PSI after that it generates too much heat to be worth it?

wondering what would happen if you could push 12-14psi and keep it cool..?

blow out spark plugs or gaskets maybe?

Efficiency is too vague in reality. There are many relatives. The performance map of the gen5 m90 shows it's the happiest in an island of around 6psi spinning at around 6000rpm but really who cares because it's only pulling in about 300cfm of air then. I run my m90 to 15+psi. It goes like hell all the way up to the 6800rpm or so and the belt doesn't slip so I'm happy with however it's doing it. Like any fluid pump the supercharger's ability to pass more air through it rapidly decays if it's fighting against more head pressure (boost) so that means yes, there is a point where pushing too hard will start reducing peak power no matter how much cooling you have under it. The more fuzzy issues of managing the heat, keeping the belt from slipping, and keeping the blower from dying in a short period of time tend to get in the way before you can really hit that more absolute limit.

The thing about positive displacement blowers is that if you're maxing out its pressure ability, it doesn't matter much if you go bigger in size. The pressure (boost) is a result of the engine resisting that amount of airflow. This means that putting an M112 blower on the same engine because your m90 is maxed out doesn't really work out because you're still gonna hit that same pressure limitation flowing the same air. You only gain a little bit of thermal efficiency up at that point from spinning it slower. On the other hand if you have a different type of blower than can operate at a higher pressure ratio like a TVS or whipple, you can make more power even with a smaller blower provided the engine and blower are happy with the terms. That one regal guy threw an undersized tvs on his L67 and got a nice increase from that.

Cody, why did you decide on an FGT over a TVS, whipple, HTV1900, 2300, etc?

You mustve researched pretty hard before dropping coin?

He saw some guy on Facebook selling one off of a GTP and got jealous

mostly cost and fitment
I was kinda hoping edelbrock would get back to me about my inquiry on their generic TVS 1740 they had a flyer for a while ago at sema but that didn't happen. I see whipples on ebay and whatnot but I don't like how they are usually old obscure application kits that they want stupid amounts of money for. A guy I've been talking to is working on fitting a gt500 blower to a 3800 and that got me lookin around some more. I don't like how those blowers are set up at all - it doesn't work out so nice as the FGT blower aught to otherwise i'd go straight to the tvs version of that.
As a side note, I might be alone on this one but i think those harrop htv castings are just freakin ugly lol. It's a shame because the generic style 1900 I think would really be the way to go if you wanted to spend the money on it. Anyway those are still 3x more expensive than what I paid for the FGT blower taken off a brand new crate motor.

I'm holding off on going any further with the main adapter plate/ic business until I have a chance to see how much actual hood clearance I have and where it lines up the best for the belt. I'll have an opportunity to do that when I do my block swap in a couple weeks.


That's the current plan assuming I'm the ballpark for lining up the belt and also assuming I go the Ed LaBarge route with the intercooler. With the amount of work I'll be doing on it, I might as well make it all myself but I don't want to redo the stuff that has already been done and works. That green 2D model is a gen 3 blower by the way.

My intention is to take off the OEM pulley and fit a zzp/intense MPS hub to it. I don't know until I get the original pulley off but just by eye it actually looks like the same size shaft. Only thing is the pilot in the middle of the shaft you use to thread into and press on a pulley or hub isn't threaded on this blower, nor is it venting the gearbox - it's just a blind hole.

The zzp modular pulleys should work really nice from what it looks like.





The northstar flange is done basically. There was some minor revision but nothing worth fussing about.

James and I came up with the idea as a joke to just make a setup to run a northstar and an L32 electric throttle body together and hot-wire the L32 one to open up when the primary northstar throttle body is all the way to 100% TP. What killed the joke was everything in front of the throttle body. Even though they're both 75mm blades, the northstar has a 4" opening. The L32 has a 3", not to mention I still need to get a maf in there somewhere. I hadn't really gotten anywhere good with another solution so for shits & giggles I decided to hack up a L32 throttle body and see if I can convert it to a mechanical and to my genuine surprise I'm actually getting somewhere with that.

Behold the L32-northstar hybrid throttle body

This is a bad picture (sorry) but the L32 tb has a kind of funky bore to it to provide finer part throttle control which makes sense since those cars don't utilize a discrete IAC circuit like the conventional cable throttle bodies. In any case the northstar blade even though it's just a tiny bit thicker seems to fine in there. I have the whole pivot shaft/throttle cable cam and everything in the L32 tb housing (after much hacking and machining).


This is the side that was just blocked off with a pressed in plug. I removed the plug and then machined it to fit the northstar's spring retainer. I was doing all sorts of measuring and tricky b.s. with this just to find out that the existing bearing limits how far in I could machine the main step for the spring retainer and therefore the whole shaft assembly and it just happens to be at a depth that's pretty much perfect with respect to the throttle blade inside the bore.



On the other end, I needed to cut the entire motor/gear/control unit right off and machine it to accommodate the northstar TPS. This involved the same kind of machine work as the other side but I also needed to make an adapter ring to mount on there since the housing didn't have the meat where I needed it to nicely mount the TPS. Plus, that gives me a piece I can alter for the tps positioning without messing with the rest of the housing. I will need to remake that actually because I was just a hair off with the clock angle of the tps but I was kinda figuring on that from the start.

Now I just need to come up with something for the return springs to hook on since obviously there's no such peg on the L32 housing, a throttle close stop, and I need to come up with something for the cable bracket. That will more likely attach to the flange that both throttle bodies will mount up to. So if this pans out, I'll have dual 75mm throttle bodies for this thing and it'll have totally factory-like part throttle manners. Dual 3" shouldn't be that bad to collect into a 4" pipe situation for the maf and intake.

This project is getting super fun!

and random time... (since I accidentally uploaded it to my photobucket and it's 2am)

OOO! very cool. I like the whole multi-stage throttle idea.

James showed me a way to move the alternator. I guess they did this on erics riv and it worked well. Basically if you get rid of one of the heater pipes on the tensioner, you have room to swing the alternator back away from the blower. Then I just make a bracket or two to bolt the other points with similar to a normal zzp alternator relocation. That bottom alternator bolt going through the tensioner into the head is the most structurally important and this maintains it so that's awesome.


I'm going to hack off that heater connection at the red line and then plug it off.


Then I remove the factory plug from the end and put in my own fitting. I made a fitting to go in there and let the original heater pipe seat in just like it does on the original fitting. It will move the heater hose back and around just a tad so hopefully it works without trouble but I can play with it if it's a problem.

Only downside to this I see is it will make the rear spark plugs a bit harder to get to. I don't mind having to remove the alternator to do them but I just hope I don't need to disconnect a heater hose cause that would suck. I don't think it'll be that bad.

I've been away for a bit, came back after my co-worker saw three gen8s in a row to check if y'all had inexplicably relocated to South LA... and saw this. Turtleman... just wow. Even with a 'smaller' throttle body, you're gonna be looking at some crazy gains. My question is, does it still count as a sleeper if it sounds like an F14?

The pulley adventures/maybe useful to people doing pulley swaps


tapping the hole so I can use the puller tool




Oh I had to make a special plate


and this is about when I learned the FGT shaft is like 16 c-hairs smaller than the m90 shaft


so i made a copy of a zzp/intense hub except with the bore to press onto my shaft


and bam!

huh. You really wouldn't be able to pull this off if you didn't have the fabrication skills you do now. Feels good doesn't it?

Looks like you'll have to machine the snout down if you want to go any smaller than that.

matt270avian wrote:

Looks like you'll have to machine the snout down if you want to go any smaller than that.

Captain Obvious, ladies and gentleman.....

Awesome shit turtle. However, I can't help but to think that your heads are going to fly off with a pulley that small (on that blower).

Abaddon wrote:

Captain Obvious, ladies and gentleman.....

Defender of the known!

Abaddon wrote:

Awesome shit turtle. However, I can't help but to think that your heads are going to fly off with a pulley that small (on that blower).

And then we will finally see what a CNC block girdle looks like...

I want that 2.7"!!!!

3.6" and 3.4" are on the way!

turtleman wrote:

It's looking like this is the way to go. With the mps now installed, The belt lines up. I didn't do anything real fancy to check it but by eye it looks perfect. For hood clearance, I basically just sit it on the existing 2.25" ic with 1/4" spacers under the blower as well and the hood closes fine. It seems like the biggest concern would be the throttle body area. It seems like I'm gonna have to situate the northstar tb upside down just like on the m90 now and maybe mill away that hump at the bottom (which will be at the top) for the vacuum nipples the older northstars/ls1 tb's have. Anyway the plan with the modified Ed I/C means I'm going to have a 2.375" tall core so we're looking good for that.

A couple side-by-side shots









I don't even think it looks weird or anything. totally stock

Thanks for hookin it up with the big pulleys Charlie!