my build thread, e30 with a 9 inch

[chikinhed]

Next time I have to do my head gasket I'll hit you up for your head stud hole jig. Hopefully not soon.

Sent from my GTX3582R

[djborya]

I can't say they are nice cars or particularly well engineered, but all I am saying is put 700hp in an e36, and 700hp in a fox body with some bolt on suspension and see which gets to the end of the 1/4 first. If the goal is to go drag racing (which mine is) then all BMW chassis are turds. Even for a handling car the latest mustangs are a peach.

http://www.motortrend.com/roadtests/...n/viewall.html

I have to disagree with the BMW suspension/chassis comment. I'm using stock BMW chassis/suspension in my car
I'm getting consistent 1.35 to 1.38 60ft times and running well in to the 8 second range. If I spend the time and money to put the solid rear with a 4 link, my car I better be running low 7's.

[someguy2800]

Boris that is an awsome 60 foot for a stock IRS car, but I've seen street driven fox bodies run 1.2 on 275 radials. Of course that with a different powertrain so it not a fair comparison. Just curious what did you pull on the stick? Your car is a beast by the way! 8.80 is getting it done!

[djborya]

I was getting 1.38~1.40 with stick and 245/45/17 drag radials. I am confident that I could get in to 1.2x if I had a tighter converter. I am using 3.23 gear in the rear and my first gear is 1.83 so the car leaves really soft and I get lots of converter slipThe Irs in E30 is basically a same thing as the ladder bars if u ask me. The key is to keep the suspension travel to a minimum in the rear to allow for a firm plant of the tires and to keep the tires from loosing the contact patch.

[5mall5nail5]

The other factor is, and no offense to Boris, but Fox bodies are cutting those times consistently and are down a lot less between runs. Between the motor, the trans, the rear, the body, etc., they've got proven routes that have minimal pioneering aspects. It might not be as fun in a Fox body if you like the engineering aspect of building the E3x, but there's something to be said for going through Summit and S&W catalogs and building a 7 - 8 sec car mail order.

[someguy2800]

Right now the limit is the powertrain not the chassis. I do believe your car is capable of 1.2 60 foots if you can get the car on the converter hard enough out of the hole, which will probably mean a tighter converter and a hard nitrous hit right out of the hole. I think once you get the power delivery dialed in the limit of what the chassis can hook won't be too far away.

My goal is what Jon noted above, consistancy and reasonable reliability. I'm hoping for domestic like reliability of going to the track and running 10-15 passes in a day and driving home. My friends with stangs and F bodies make me jelous! With modest power levels I think the only maintnance thing I will have to worry much about will be clutches, which I am working on a better solution to that now. I don't see that being realistic on any bmw IRS.

[djborya]

I understand your concerns. But I wont be the first one to tell u that most of my issues arise from the Bmw pwerplant. I ask alot from it, but my rear hasent given me any ussues in close to 2 years. If I wanted a consistent car I would go with a lsx powerlant ,Th400,and a slid rear.

[BMWSOB]

Everyone knows e30s are God's chariot and best drag car in the whole world. For shame talking bad about it.

[someguy2800]

Finally back to work on the car! I've been working a lot of long hours and I need to spend some time with my wife as it looks like she got a job about 2 hours away.

todays goal is to plumb the waste gate and build a downpipe. The downpipe and waste gate outlet will be mild steel with thermal wrap going under the car and ill be building two exhaust systems. The race pipe will be a 4 inch straight pipe exiting in front of the rear passenger wheel made out of .063 alluminum. Should save about 15 pounds over steel. The street exhaust will split into two 3 inch dynomax vt's exiting out both sides. The idea is to make it easy to swap out or remove for service without having to jack the car. Since the car rides fairly high ill have plenty of clearance




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Dont worry about the nasty head and block, those are just spare parts for fit up

[auaq]

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Dont worry about the nasty head and block, those are just spare parts for fit up

Huh! Don't know what are you talking about. Looks clean to me!

[someguy2800]

4 inch downpipe. Lots of room. I could fit 5 inch if I wanted.

[auaq]

Aren't majority of members here running 4 inch downpipe? If so, what are the pros and cons of having different sizes? Better flow characteristics? Back pressure?

[futureroadracer]

Nice!

[highboostingm3]

This is looking GORGEOUS!

Nice and tight.

[someguy2800]

Aren't majority of members here running 4 inch downpipe? If so, what are the pros and cons of having different sizes? Better flow characteristics? Back pressure?

Bigger tube means less velocity which means more stable flow which means less back pressure which means mo betta.

[auaq]

Hmmm ... For some reason I thought that three inches was good enough and not to go for any smaller than that or bigger than that.

[someguy2800]

It's mass flow dependent. Say for example a 600 hp car move roughly twice the mass of air as a 300 hp car, so it needs twice the cross sectional area to maintain the same velocity

[auaq]

I see.

[E36 HateR]

Fab looks great!

And also doesn't dumping the wastegate to atmosphere help vs dumping into exhaust with back pressure.

[someguy2800]

It probably will depending on how restricted the exhaust is. I will probably be recirculating for noise reasons

[DADx2]

Fab looks great!

And also doesn't dumping the wastegate to atmosphere help vs dumping into exhaust with back pressure.

Food for thought on this.... When I was running 3inch exhaust, with open dump WG, I dyno'ed at 598whp .... tied the WG back into the exhaust (at a sharp angle thinking it would help with flow into the exhaust) then re dyno'ed (2hours later)... 560whp was the result. Needless to say, I changed it right back to open dump.

Now that I am 4 inch oval, I am (loosely) considering tieing it back in for noise reasons, but really don't want to go through it to find out that power is lost. I guess there is only one way to find out.

[5mall5nail5]

FWIW, I almost considered redoing my down pipe in 3 or 3.5" to alleviate my boost creep issue. Still creeps slightly, but I am ok with it. Your manifold has a good opportunity for wastegate placement if it can fit in the car. The more free-flow the exhaust, the more likely the exhaust will be to just go through the turbine housing. When I had a 3" down pipe I had a really inefficient wastegate placement and it worked flawlessly. 4" has been more problematic.

[someguy2800]

Food for thought on this.... When I was running 3inch exhaust, with open dump WG, I dyno'ed at 598whp .... tied the WG back into the exhaust (at a sharp angle thinking it would help with flow into the exhaust) then re dyno'ed (2hours later)... 560whp was the result. Needless to say, I changed it right back to open dump.

Now that I am 4 inch oval, I am (loosely) considering tieing it back in for noise reasons, but really don't want to go through it to find out that power is lost. I guess there is only one way to find out.

Thats really interesting. how sharp of and angle was it? I wouldn't think it would make much difference if it was a shallow angle, like 30 degrees or so. I might have to do some research on that. Now you have me thinking about dumping on the race exhaust and recirculating the street exhaust.

[DADx2]

I would speculate that it was a 30/35 ish degree entry angle. I didn't get any pics of it since I changed it back almost immediately.

[Kame36sedan]

One other thing, I run a dynomax VT thats 3" it is v banded on right at the dynomax. I was tuned with the dynomax installed, removed it one day to enjoy the exhaust tones while cruising and it was a night a d day difference. Spool was quicker and it felt like it pulled a lot harder. Not sure if it was a common butt dyno mistake but I definitely felt a noticeable difference.