Guestimates...

[Sykohtic]

Okay, typically I'm not a huge fan of the type of thread I'm posting, but after a discussion with another E30 owner who does engine building about what I want to do with my M20, my curiosity is getting the better of me...

So yeah, the question is with x upgrades, what's your power estimate for my car...

ON 93 OCTANE PUMP GAS

-Racehead ITB Kit w/custom airbox
-IE 3.0L Stoker Kit
-304 degree cam
-IE Long tubes w/ full custom catless exhaust and custom high flow X-pipe to a dual muffler system at the rear
-Port and polished head
-HD Rockers
-Performance ECU (Might just go with the one listed on the Racehead website as I know it'll read all the signals I'll be throwing at it) and tuning
-MAYBE uprated fuel injectors if I need them

I think that's everything on the list (I think).... For now, just assume this is going under the car through a G260 and the stock 3.73 LSD

Power goals were originally 300-320 bhp, but after a recent conversation with a guy who builds engines and is currently working on building a very high hp M20, he thinks I'll have power potentially well over those figures. So do you peeps think he was right and if so, by what margin greater over the 320 would you think? I know this is all a very tedious question, but I figure whatevs.

*NOTE* I'm not a fan of these types of threads either. It makes me sound like a massive newb. Let me be clear... no, I don't want an S50/2 or a M20 turbo. I did rather entertain the idea of a supercharger, but making a bunch of power and staying NA with an M20 makes me more happy.

[Bullhead]

Are you assuming RWHP or at the crank? There are a couple cars on YouTube that have similar setups claiming around 325 at the wheels but idk, I have never watched one dyno in person.

[4x4_e30]

This is like the 4th thread this week, lol. Theres a 2.8 liter m20 making 400 crank horsepower on e85 and 14.5:1 C/R.
http://www.r3vlimited.com/board/show...91&postcount=9

[Sykohtic]

Are you assuming RWHP or at the crank? There are a couple cars on YouTube that have similar setups claiming around 325 at the wheels but idk, I have never watched one dyno in person.

I'd say the crank in this case, at least, my original 300-320 hp power goal was based on the crank. That being said, drivetrain loss for a manual lsd equipped e30 isn't outlandishly large, its like 30 hp on an all factory setup (though I guess that is a pretty good chunk of power). I would assume that though drivetrain loss is measured in percentage, 30-ish hp is going to be a good approximation of drivetrain loss... If theres any legitimacy to the claims of the YT, I guess that means 350-ish crank hp (bhp) isn't out of the question...

[Sykohtic]

This is like the 4th thread this week, lol. Theres a 2.8 liter m20 making 400 crank horsepower on e85 and 14.5:1 C/R.
http://www.r3vlimited.com/board/show...91&postcount=9

Lol I've been fighting myself on even posting it for like two weeks now. It was a moment of weakness... Thanks for the link.

That is pretty crazy though... 400 hp out of a 2.8L. Thats impressive even with the fact that they're running e85... The guy who I talked to claimed he was running close to 300 with a built 2.8L with a race cam, oversized valves, and a few other things and a really aggressive tune, on apparently pump gas. If an e85 drinking 2.8L that's built is running 400 crank, makes me think the guy was maybe being pretty serious lol e85 adds a fair bit of power no lie, but its fair to assume that if that motor is running 400, a similar motor on 93 could be running 300. The guy seemed convinced I'd be running well over my power goals. This adds a little bit of legitimacy to those theories.

[TobyB]

With a turbo, sure, those numbers sound believable...

t

[ak-]

Somebody call Nando or Digger so they can yell at you

[Sykohtic]

With a turbo, sure, those numbers sound believable...

t

I'm actually 100% certain I can make around 300whp at the least without a turbo. It's more expensive to go NA, but I'm pretty sure I'll have a better torque band and more uasable torque in general that way.

[Poorboyz]

Your name suits you.

Sent from my 831C using Tapatalk

[ThatOneEuroE30]

May I ask what you do for a living. Cause I need to get into what ever profession your in cause you must have deep pockets

[SkiFree]

The figures you're giving are attainable with enough time and money (that's a very healthy parts list)....Just not on 93 octane applicable compression ratios.

What you're idealizing is a full race engine with race-prevalent compression ratios (>12:1) on race gas (whose life is measured by hours/season not miles) and lots of tuning (with a peaky power curve).

[4x4_e30]

The biggest mistake almost every person trying to make big power on the m20 makes, is starting with the 885 head. Every M20 that's in the 300rwhp range started with either an "inferior" AMC casting, or used the 731 head. E21JPS even got his 200 "ETA" head to flow up to his target numbers.

Apparently velocity and low-mid lift efficiency are much more important than huge flow at maximum lift. It makes sense when you consider the valve spends a lot of time in the low-middle of it's lift since it has to ramp open then ramp down every time.

Also, there's the combustion chamber shape. The M20s you see making big power have pentroof chambers and flat pistons with a huge squish area. The 885 is semi hemi and relies on a funky piston shape to make the squish band. In addition, being a hemi design, there is much more area for the combustion event to bleed off heat. With the pentroof, all of the combustion is confined to a much smaller space, decreasing the amount of time it takes for a complete burn to take place and reducing parasitic losses.

Another issue with the M20 is that they took a very shallow approach on the ports vs valve angle. Raising the ports and filling the bottom seems to be the ticket.

It doesn't take a ton of money if you have a couple extra heads around, a lot of free time, and a flow bench.

[SkiFree]

The biggest mistake almost every person trying to make big power on the m20 makes, is starting with the 885 head.

Not true. That is way too broad of a claim to even begin to take you seriously (even if you have some other "ok" points).

[digger]

The biggest mistake almost every person trying to make big power on the m20 makes, is starting with the 885 head. Every M20 that's in the 300rwhp range started with either an "inferior" AMC casting, or used the 731 head. E21JPS even got his 200 "ETA" head to flow up to his target numbers.
Apparently velocity and low-mid lift efficiency are much more important than huge flow at maximum lift. It makes sense when you consider the valve spends a lot of time in the low-middle of it's lift since it has to ramp open then ramp down every time.
Also, there's the combustion chamber shape. The M20s you see making big power have pentroof chambers and flat pistons with a huge squish area. The 885 is semi hemi and relies on a funky piston shape to make the squish band. In addition, being a hemi design, there is much more area for the combustion event to bleed off heat. With the pentroof, all of the combustion is confined to a much smaller space, decreasing the amount of time it takes for a complete burn to take place and reducing parasitic losses.
Another issue with the M20 is that they took a very shallow approach on the ports vs valve angle. Raising the ports and filling the bottom seems to be the ticket.
It doesn't take a ton of money if you have a couple extra heads around, a lot of free time, and a flow bench.

The thing in common is a head that flows atleast ~200CFM through the whole intake tract (not just a bare head) a well matched combination with proper inlet and exhaust tuning and huge lobes on the cam. These are fully built race engines

I don’t agree with low lift and midlift importance blanket statement, it doesn’t make any sense to make blanket statements when there are camshafts ranging from 10mm lift to 14.5mm lift and duration 250 to 330degrees. It depends on the application and the cam.

i feel the importance of flow needs to be based on the cam specs and to account for peak piston speed ( peak flow demand) and the cam lift where the port air speeds are highest and the port chokes. If you do some basic analysis of piston speed vs crank angle and cam lift versus crank angle it will become apparent that mid and high lift on a performance m20 stoker with decent cam will delay choke and make more power at higher rpm more effectively. With a stock cam the importance shifts to flow at lower lifts IMO.

No M20 has a pentroof chamber at all, the M50, S50 i.e 4V cylinder head etc have pentroof chambers. The most powerful M20 that is publically known uses the 885 semi hemi design with its angled squish band so if you think this is bad you need to take a step back for a bit as it seems to work well.

The 731 is similar but the squish pad is flat and the chamber ends up a little smaller making it slightly easier to get higher CR. The advantage in the 731 chamber is being able to use a flat top piston successfully retain squish and being able to set up the squish clearance easier. There is no evidence that it is better for making power over the 885 chamber.

[digger]

Okay, typically I'm not a huge fan of the type of thread I'm posting, but after a discussion with another E30 owner who does engine building about what I want to do with my M20, my curiosity is getting the better of me...

So yeah, the question is with x upgrades, what's your power estimate for my car...

ON 93 OCTANE PUMP GAS

-Racehead ITB Kit w/custom airbox
-IE 3.0L Stoker Kit
-304 degree cam
-IE Long tubes w/ full custom catless exhaust and custom high flow X-pipe to a dual muffler system at the rear
-Port and polished head
-HD Rockers
-Performance ECU (Might just go with the one listed on the Racehead website as I know it'll read all the signals I'll be throwing at it) and tuning
-MAYBE uprated fuel injectors if I need them

I think that's everything on the list (I think).... For now, just assume this is going under the car through a G260 and the stock 3.73 LSD

Power goals were originally 300-320 bhp, but after a recent conversation with a guy who builds engines and is currently working on building a very high hp M20, he thinks I'll have power potentially well over those figures. So do you peeps think he was right and if so, by what margin greater over the 320 would you think? I know this is all a very tedious question, but I figure whatevs.

*NOTE* I'm not a fan of these types of threads either. It makes me sound like a massive newb. Let me be clear... no, I don't want an S50/2 or a M20 turbo. I did rather entertain the idea of a supercharger, but making a bunch of power and staying NA with an M20 makes me more happy.

hp is going to be governed by the induction flow mostly and the head and cam shaft are most important aspect given you have a proper intake listed on your spec sheet. you should be able to make your target