Guestimates...

[digger]

Unless he goes with huge compression gains, premium fuel is good enough, and you don't have to worry about delivering 30% or so more fuel - and depending location e85 isn't readily available everywhere here in the states.

i agree and only mentioned it because he mentioned flex in his post but no mention of CR

[Sykohtic]

You might just want to start with a turbo on your m20. Best bang for the buck and with a junkyard motor, you can reach well over 400whp.

Yeah, it'd be easy enough to go order a kit from Kam and turbo it all to bits, but everyone does that. Its always turbo or S50 swap. And while if it ain't broke, don't fix it, if I did my car that way, its not all that special, you know?

If I'm gonna boost, I'm gonna SC. I want boost from idle and beyond, not when I hit 3 grand, which is why I want to run a roots type, and not a centri. Supercharger on a high boost setup plus the torque from extra displacement seems to me like it would be pretty potent down low, then have plenty of hp up top when it hits full boost.

I'm not all about making gobs of horsepower for value, which you are right, a turbo is the best way to accomplish that. I want something different and something that feels the way I want it to, as well as something off the well traveled road.

If you want all out N/A M20 up the comp to run E85/flex and a bigger cam.

I didn't think you could go bigger than a 304 without serious work on the geometry? They did mention being able to up the compression masses, but said it'd basically only run on racefuel at that point, so that's not of much use to me on a car I still want to be able to sustain street wise, so I want to make tons of compression, but can only make so much before it's too much for pump gas to run it at all. But as we've discussed earlier in the thread, I definitely will be having flex fuel become a part of things regardless; they showed me the flex fuel unit they're running on an STi that they had in the shop when I visited, and its pretty easy for them to run the unit into the standalones that they mentioned, at least according to them.

I will say they also mentioned going less for the big 3.0L stroke. Do a smaller stroker and use the smaller to make more compression. I would assume thats gonna sacrifice some torque bottom end though, given I know theres gonna be give or take no matter where I go on this one.

[ForcedFirebird]

Either type of blower is going to give near-instant throttle response - they are both belt driven ;)

In post #42 you are mentioning some tall orders. What kind of budget and time-frame are you working with?

[Sykohtic]

Either type of blower is going to give near-instant throttle response - they are both belt driven ;)

In post #42 you are mentioning some tall orders. What kind of budget and time-frame are you working with?

Yes they're both belt driven, but the physics of a centri are quite different from a roots. Centri makes very little boost in the low end, and doesn't really come on until around 3000 rpm, and even then, its not making full boost until full rpm. There is definitely a spool up margin for centri, like a turbo, they are not positive displacement. I suppose you could do some fancy work with the pulley and get it to spool faster.

For some more info, or to check my reasoning:
http://www.downingbrothers.com/supercharger/types.htm

The project is going to be likely a 3 year affair. So the large budget is going to be pretty well spread out as far as I know at the moment. But regardless, it is gonna be pretty hefty. Not to mention I'm still gonna have a load of body work and some electrical to work out...

[digger]

Yeah, it'd be easy enough to go order a kit from Kam and turbo it all to bits, but everyone does that. Its always turbo or S50 swap. And while if it ain't broke, don't fix it, if I did my car that way, its not all that special, you know?

If I'm gonna boost, I'm gonna SC. I want boost from idle and beyond, not when I hit 3 grand, which is why I want to run a roots type, and not a centri. Supercharger on a high boost setup plus the torque from extra displacement seems to me like it would be pretty potent down low, then have plenty of hp up top when it hits full boost.

I'm not all about making gobs of horsepower for value, which you are right, a turbo is the best way to accomplish that. I want something different and something that feels the way I want it to, as well as something off the well traveled road.



I didn't think you could go bigger than a 304 without serious work on the geometry? They did mention being able to up the compression masses, but said it'd basically only run on racefuel at that point, so that's not of much use to me on a car I still want to be able to sustain street wise, so I want to make tons of compression, but can only make so much before it's too much for pump gas to run it at all. But as we've discussed earlier in the thread, I definitely will be having flex fuel become a part of things regardless; they showed me the flex fuel unit they're running on an STi that they had in the shop when I visited, and its pretty easy for them to run the unit into the standalones that they mentioned, at least according to them.

I will say they also mentioned going less for the big 3.0L stroke. Do a smaller stroker and use the smaller to make more compression. I would assume thats gonna sacrifice some torque bottom end though, given I know theres gonna be give or take no matter where I go on this one.

There are few aussies who looked at use a twin screw from an AMG C32 on S50B30/32 which I quite like in terms of the power delivery it could bring but nothing ever finalized or completed AFAIK.

If you want to run it on pump gas on the street maybe forget about flex fuel if you go down the N/A route due to the extra costs to run E85 from hardware point of view and tuning perspective. With Boost and E85 it probably makes sense as it will be more beneficial.

Bigger cam is possible but you need the right valve springs, and retainer combination so that you have the right seat and nose pressure (force) and don’t get coil bind, and the retainer doesn't hit the valve stem seal but it’s nothing a head guy can’t sort out. You will be limited to about 12.5mm lift with a conventional off the shelf grind. If you want to drive on the street then yes don’t go crazy it will get old pretty quick.

I would tend towards as much stroke as you can if tending more for streetcar and a bit less stroke for track oriented. The peak hp difference will be much of a muchness but all else equal a bigger stroke will make more torque and the peak hp peak will be a lower rpm.

[Sykohtic]

There are few aussies who looked at use a twin screw from an AMG C32 on S50B30/32 which I quite like in terms of the power delivery it could bring but nothing ever finalized or completed AFAIK.

If you want to run it on pump gas on the street maybe forget about flex fuel if you go down the N/A route due to the extra costs to run E85 from hardware point of view and tuning perspective. With Boost and E85 it probably makes sense as it will be more beneficial.

Bigger cam is possible but you need the right valve springs, and retainer combination so that you have the right seat and nose pressure (force) and don’t get coil bind, and the retainer doesn't hit the valve stem seal but it’s nothing a head guy can’t sort out. You will be limited to about 12.5mm lift with a conventional off the shelf grind. If you want to drive on the street then yes don’t go crazy it will get old pretty quick.

I would tend towards as much stroke as you can if tending more for streetcar and a bit less stroke for track oriented. The peak hp difference will be much of a muchness but all else equal a bigger stroke will make more torque and the peak hp peak will be a lower rpm.

Twin-screw... I do like the sound of that, were I to have the ability to find one at the right price, the mounts probably wouldn't be too hard to figure out, I'm sure I could probably make that work just as well as a simple roots type on a M20, but the twin scroll could make more boost. If I went boosted.

It's interesting, and I'll keep that in mind about cams. I'll probably stick to the 304 since, as the general consensus has been stated, more than that would likely be just annoying on the street, plus the 304 is already sacrificing down low power that the stroker and possibly boost would have to make up for.

I'm a little on the fence now about the stroker. I like the way 3.0L rolls through my mind, but at the same time, 2.9 seems like a good street/track compromise, especially if boosted... Hmmm...

[ForcedFirebird]

An Eaton m90 is enough to deliver a 9 second pass. Cost is about $150.

[Sykohtic]

An Eaton m90 is enough to deliver a 9 second pass. Cost is about $150.

This remains VERY true. And that being said, picking up a M90 is also like a grand cheaper than ITBs, so there's also that... lol

[Sykohtic]

Its been a while since I've posted. So here's some updates.

I've had to postpone meeting with 42 Autosports for the time being. The car is begging for new pads and driving it all the way to Concord on questionable brakes in traffic isn't my idea of a great time.

Ive somewhat swayed from a NA build for this particular car. At some point I'd love to build an all NA M20 monster, but for now I'm prepared to settle for a boosted M20 monster. Ive decided to supercharge it. So now I have a few more questions...

Eaton M90 or M62? The M90 is easier to find and has a some benefits as far as boost climb rate, but the M90 is detailed as being designed for 3.0L plus, and going SC, I was going to not go full 3.0L, and was going to go to a smaller stroker and then have the supercharger fill in the price gap between it and the larger stroker. I wouldn't think that if I went 2.9 that it would be much of a difference, but I know every little bit counts. This is versus the M62 which is designed for smaller motors to begin with. The problem is it takes more rpms to spool it to higher boost levels and it seems a little more difficult to track down, though that just might be my area. I guess in reality I'll likely be fitting a smaller pulley for more boost anyway, but still. I know that I CAN make it work, but I want to know it I SHOULD.

New power goals are in the 360-400 bhp range. I leave a wide range just because I'm not sire what the hp exchange rate with the roots blower is going to be. I know I'll probably be sacrificing a little bit of peak hp as compared to a turbo car making the same boost, but I figure in exchange, it'll pull harder in the low and mid-range.