Superchared diesel inside here...

[david_lee]

this may be a moot point as it sounds like you are leaning heavily toward scrapping the supercharger for a turbo, but...i think i can see what you mean about machining the snout. however, there's always another option. it would mean more work and a bit more money, but it would look good. if the super charger pulley can't be made any smaller, then find a larger crank pulley as you and others have mentioned, but you also commented on how it would affect your water pump. this is where it could cost more; since you are upping the crank pulley, find or have new pulleys made for everything else on the front of the engine so that it all still performs as it should.

88 ford,
they are capable of doing lots of small work in the shop. all that is required is good, accurate drawings to work from. if you can take precise measurements and draw it up, send it to me and i will get in contact with the instructor to see what he thinks about what kind of material to use and what tooling will be required. the spring semester is usually the advanced cnc machining class for the students that are getting ready to graduate. prime time to have it done.

 

[lotzagoodstuff]

I think the crank pulley is close to 7" or so. It is hard to get from what I had to work with at the time. The more I think about it, the more likeley I will be putting on the remote mount turbo.

SWS

I'm sure you're already familiar with them, but just in case, check out Squires Turbo Systems at ststurbo.com. I was shocked at how little they have in the way of sheilding for the intake air, but they have several applications/vidoes where they are flogging the crap out of trucks in mud/sand and they seem to stand by their product.

Good luck whichever way you go: my vote is for the supercharger, but either one is way cool in my book

 

[MUDKICKR]

be better off to make a jackshaft and have different sized pulleys on each end. but sounds like your already set to take it off and do a turbo. if you do remove it i will pay shipping so you can send it to me and i will research with it some more.

 

[88 Ford]

Don't give up man. You are so close to doing something unprecedented on an idi!! But if you do decide to go in another direction, don't totally dismantle it, sell it and let someone else have a crack at finishing what you started. It would be awesome to seeing it make around 10psi.

 

[wmoguy]

Is there a point of too much boost at idle or "down low" that becomes unsafe? I realize thats not the case in SWS's setup (yet) I ask the question more out of personal intrigue. Would somewhere in the vicinity of 5-7psi @ or just above idle be safe assuming it was efficient positive pressure remaining throughout the power band?

 

[ocnorb]

Is there a point of too much boost at idle or "down low" that becomes unsafe? I realize thats not the case in SWS's setup (yet) I ask the question more out of personal intrigue. Would somewhere in the vicinity of 5-7psi @ or just above idle be safe assuming it was efficient positive pressure remaining throughout the power band?

I wondered the same thing; what is the peak cylinder pressure at low rpms that an IDI could handle?

There is a guy at work that races Supercharged Cobras and he tells me that the bottom end of an IDI won't hold together with boost at low rpms. I'm not so sure; especially with a slightly lower compression ratio.

I'm really rooting for SWS to continue his pioneering efforts here! Good job so far and thanks for documenting your work!!

 

[Fordman75]

I don't want to add fuel as I run close to 900 when I put my foot to the floor. It would probably go higher, but I watch it and adjust accordingly. I think the baby moose puts out plenty of fuel for this.

And Fordman if you are trying to patronize me then I will stop responding to you. As far as almost 8 years, you almost have as many as I do. Also, if you look, some of the 5.0 guys run them. AED runs/ran them on the 4.6. Rousch STILL runs them on the 4.6 blower kits they use now. I can get some vids for you if you do not believe me, but you can probably youtube as well as I can. None the less, I used the 90 cause I have a few of them lyin around. I do not have any 112s anymore. I DO have a turbo, which will probably be what gets added.

SWS

I was trying to help but no one wanted to listen so I just decided to go with the flow. The M90 was design for engines up to 5.0L. But there is one hell of a difference between a 4.6L/5.0L and a 6.9L/7.3L. To make a decent amount of boost you are going to have to spin the M90 much faster then a larger one. The eatons a not very efficient at higher speeds. Which means some very high intake air temps. Which means less power and a higher egt's. There is a reason the Cobra and GT500 guys swap to Whipple SC's!! Oh by the way Roush uses the new Eaton TVS superchargers on their 5.0L Coyote kits.

Think of it this way you can haul a heavy load with a truck powered by a 5.0L if you have the right gearing. But it will have to work a hell of a lot harder then a truck with an IDI would. Same thing goes for the blowers. The smaller blower is going to have to work a lot harder to come anywhere close to the results of a larger one.

If you had a few M90's laying around you should try running 3 or 4 of them!! It would make a fun ride and make enough noise to drive the neighbors batty!!

Seriously good luck on which ever way you go ( the current set up or turbo ) . You did a nice job setting up the blower. I've brought up Eatons in the past for the IDI's but none seemed to think it was a good idea.

I'll shut up now.

Is there a point of too much boost at idle or "down low" that becomes unsafe? I realize thats not the case in SWS's setup (yet) I ask the question more out of personal intrigue. Would somewhere in the vicinity of 5-7psi @ or just above idle be safe assuming it was efficient positive pressure remaining throughout the power band?

If you are worried about the boost off idle the Eaton M112's & H122's have a vacuum operated bypass valve. With a little fab work you could convert it to a cable set up. Then just set it up to open when the go pedal is released or at a certain %. It bleeds boost off and no worries.

There is a guy at work that races Supercharged Cobras and he tells me that the bottom end of an IDI won't hold together with boost at low rpms. I'm not so sure; especially with a slightly lower compression ratio.

The IDI has a lot stronger bottom end then a Cobra does.

 

[93turbo_animal]

I was trying to help but no one wanted to listen so I just decided to go with the flow. The M90 was design for engines up to 5.0L. But there is one hell of a difference between a 4.6L/5.0L and a 6.9L/7.3L.

Please don't think I'm trying to start a fight here I just wanna know your thinking behind this and anyone else that knows feel free to chime in if I'm off in my thinking but a 4.6L motor turning at 6000 rpm would be pumping roughly the same amount of air as a 9.2l motor turning 3000 rpm which is much more then a 7.3 at comparable rpms

 

[88 Ford]

Is there a point of too much boost at idle or "down low" that becomes unsafe? I realize thats not the case in SWS's setup (yet) I ask the question more out of personal intrigue. Would somewhere in the vicinity of 5-7psi @ or just above idle be safe assuming it was efficient positive pressure remaining throughout the power band?

One of the things with a lot of boost at idle the possibility of floating a valve. That is what happened to the guy with an Empire Supercharged 6.0 PSD. But... he was running a hell of a lot more boost than. Iirc it was 70psi total. And as was said before, you would need a bigger charger to have that much boost at idle. You would have to find a happy medium between what it puts out at top end and what you get at idle. It is possible to get 2-3psi out of a M90 at idle though. You just have to have the right pulley. An M90 can make boost though on our engines. I believe 429idi did the math a while ago.

 

[88 Ford]

Fordman75, along the lines of what 93 turbo animal said, it is more about the cfm of the engine at a specific rpm than the cubic inches itself. Don't get me wrong, I understand what you are saying, I just have seen the math before and an M90 is good to about 10psi without super heating the air. But anything above that and you need an upgrade. That's why I am going with a M112 on my setup. I want more boost down low to spool the turbo...

 

[seawalkersee]

Well...I figured out a few things tonight. 1st, Im an idiot. I was chatting with a buddy about this and he threw out a few suggestions about a pulley. I checked and saw that I have a few alternators lyin around. grabbed one of them and checked the clearance. Yeah...there is some, but I may be able to shim it and see if it will push boost. I grabbed a saw and cut the old SC alternator pulley first. It fit, but wobbles since it is .668" (I think) and the Eaton shaft on this style is .64(ish)". So, .02" clearance could easily be overcome by some tape or something like that just to see if it would make boost.

So, I went to take the pulley off and what do I find? The tensioner is allllll the way relaxed. When I tested it for the blet length, initially I had it hard to install. Like grunt like you are passing a meat log, tough. I moved the mount about 1/4" and that made it right about the center of travel to put the belt on. Now, knowing it was a new belt, I should have left well enough alone, but NOOOOOOOOOOOO....I had to have it just right an now it is just wrong. What does that mean? Maybe nothing. BUT, that could be the surges of power that I was feeling when I was just crusing, just prior to going into load as I was at the bottom of the hill the first time I drove it. So if the belt is slipping now, it would not even necessarily leave any dust because of how loose it was...and there is less than 150 miles on it.

3rd, I pulled my idler pullies off of old 80s 5.0 vics. They were not idlers for those cars, they were manual tensioners. WHY did I not add the whole kit and caboodle of a manual tensioner and make it easier to add smaller pullies?

Like I said, I am an idiot.

With that figured out, Scotty is probably going to make the 2 pullies into 1 if this makes boost at idle, and I can rev it up without something bad happening with the belt being so loose. If that works, and boost climbs, that will make a big difference in what happens next. If it stays steady at like 3-5 psi (which it shouldnt since the air moved should increase more than RPM), then I will look to see how I would be able to run a jack shaft.

SWS

 

[rjjp]

Please don't think I'm trying to start a fight here I just wanna know your thinking behind this and anyone else that knows feel free to chime in if I'm off in my thinking but a 4.6L motor turning at 6000 rpm would be pumping roughly the same amount of air as a 9.2l motor turning 3000 rpm which is much more then a 7.3 at comparable rpms

I think what he is trying to say is like the 093 on my truck it will do the job for low boost levels but trying to get any real boost (read trying to blow the head gaskets) they won't do it efficiently...
From the "maps" I've found a M90 should be good for about 10-11 lbs on a 6.9, but that's pushing it to it's limit and right around 180 degree differential temperature.

 

[seawalkersee]

As far as the questions, I will try to answer them here. On the 3.8 Ford SC, this M90 is overdriven from the factory by 230%. The pulley on this one is 2.7(ish)" from the reading I have done. I have not actually measured it but will tomorrow to see how much more I can get out of it.

There are alt pullies that are just shy of 2". Depending on how much boost I gain by this, I may get one of those and have it built into the factory SC pulley.

Eatons are made fun of by people and called heatons since they start to lose efficiency at 8psi. With that, you can only move air so much, or so much air at a given RPM before it starts to heat up. The way this SC was set up from the factory was JUST like it is set up here. It does not blow into an intake, it blows out of the top, into a pipe. I have no intercooler on this yet (cause obviously I do not need one with less than 1psi of boost), but the factory car did have an air to air mount intercooler. I still have the pipes and original intake for an M90 in my garage if you have to see it to believe it.

Yes, the twin screws are more efficient. Yes I have one. No, it is not being used right now. No, I will not put it on this. And yes, it does have a purpose.

My dad saw this thing run for the first time the other day with the supercharger and was laughing when I popped the hood. He could not believe that there were 11 pullies under the hood. With that knowledge and no more, where could I put even 1 more supercharger?

I will probably go to the bone yard this weekend and get a few more tensioners. I will have to do a few more adjustments to this to make it right. Again, I am not looking for 20 psi. I would like to have 3-5 just off of idle and keep it around 10. If it is too noisy, I will sell it on the cheap to whomever wants it. Oh...and it barely hits the hood. Just enough to rub the paint off of the top. A hammer to knock in the brace and it will no longer rub.

SWS

 

[rjjp]

Like I said, I am an idiot.
No
With that figured out, Scotty is probably going to make the 2 pullies into 1 if this makes boost at idle, and I can rev it up without something bad happening with the belt being so loose. If that works, and boost climbs, that will make a big difference in what happens next. If it stays steady at like 3-5 psi (which it shouldnt since the air moved should increase more than RPM), then I will look to see how I would be able to run a jack shaft.

SWS

Yay, I want to see this work.

 

[wmoguy]

As far as the questions, I will try to answer them here. On the 3.8 Ford SC, this M90 is overdriven from the factory by 230%. The pulley on this one is 2.7(ish)" from the reading I have done. I have not actually measured it but will tomorrow to see how much more I can get out of it.

There are alt pullies that are just shy of 2". Depending on how much boost I gain by this, I may get one of those and have it built into the factory SC pulley.

Eatons are made fun of by people and called heatons since they start to lose efficiency at 8psi. With that, you can only move air so much, or so much air at a given RPM before it starts to heat up. The way this SC was set up from the factory was JUST like it is set up here. It does not blow into an intake, it blows out of the top, into a pipe. I have no intercooler on this yet (cause obviously I do not need one with less than 1psi of boost), but the factory car did have an air to air mount intercooler. I still have the pipes and original intake for an M90 in my garage if you have to see it to believe it.

Yes, the twin screws are more efficient. Yes I have one. No, it is not being used right now. No, I will not put it on this. And yes, it does have a purpose.

My dad saw this thing run for the first time the other day with the supercharger and was laughing when I popped the hood. He could not believe that there were 11 pullies under the hood. With that knowledge and no more, where could I put even 1 more supercharger?

I will probably go to the bone yard this weekend and get a few more tensioners. I will have to do a few more adjustments to this to make it right. Again, I am not looking for 20 psi. I would like to have 3-5 just off of idle and keep it around 10. If it is too noisy, I will sell it on the cheap to whomever wants it. Oh...and it barely hits the hood. Just enough to rub the paint off of the top. A hammer to knock in the brace and it will no longer rub.

SWS

there are alternative recipes for this.