my build thread, e30 with a 9 inch

[someguy2800]

I swear everyday this project keeps edging closer to being a damb racecar. Now I'm starting to think about dumping the wastegate, and lately I've been thinking about leaving out the carpet and getting some kirkey's. This is supposed to be a street car but at this rate I'm never gonna get my wife in this thing.

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I've been trying to do some reading to figure out what I actually stand to loose and can't come up with much solid data. My gut says that it shouldn't make much difference with a 4" echaust, and it would be tied in about 3 feet from the turbo, but I am finding some evidence that it can make a surprising difference. I'm thinking about doing an open dump but adding a small glass pack to it that can be removed when putting on the race exhuast. At the same time though I'm trying more and more to be weight conscious.

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The more I keep looking, the more examples I see of people losing 30 whp or more when recirculating, even when doing it properly at a shallow angle. I really never thought it would make much difference as long as it was a smooth transition and the exhaust wasn't allready a restriction. I think I'm just gonna run a seperate small muffler for the wastegate. I figure at most it should only be about a 5lb weight penalty so even if it only makes 5 hp more I will still be ahead.

[PEI330Ci]

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.

Good info.

Just a general observation, but it seems that the WG was flowing a fair amount when making that power. Not being familiar with your setup off hand, I'm assuming your turbo is relatively large?

I'm guessing that a smaller turbo, that wouldn't need much WG flow to hit 598rwhp, wouldn't have seen as much change with a tie-in.

Now I'm really starting to worry about all the nitrous I have on tap with the new street car build. Was originally thinking I'd be able to run the extra exhaust flow from N20 through a larger WG....but it may be an issue unto itself, as it's tied back into the exhaust...although about 18" down from the turbine housing. Darn street cars...

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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.

I completely get where you are coming from....I love hot-lapping at the strip.

I've found the IRS vs Live axle thing being widely miss-understood from a perspect of how the chassis is loaded. The lifting action, what pulls the front tires into the air, on an IRS comes from the center of the car through the subframe. On a solid axle, it comes from where the 4 link or ladder bar is connected, which is usually about the same place. Our IRS places the thrust force on the outside of the chassis where the trailing arms connect, where a live axle is placing this force in close location to the lifting action. These forces are in different directions, working somewhat against each other at times. The closer you can put the input of these forces together, the more control you will have on them. On an IRS like ours, these forces are a couple of feet apart, and for the most part, working against each other through the chassis' sheet metal. A 4 link can be faster than an IRS because of how it can harness the power being applied through the chassis, not primarily because of how it plants the tires.

When I was building the 330Ci, we tied the trailing arm mounting points into the roll cage structure, along with the subframe mounting points for this very reason. I don't have any proof that it worked aside from running 2 tenths faster with 20 more HP and the car was 250 lbs heavier. There were a few other things that helped like a lighter flywheel, better clutch, and slightly higher gearing, but the MPH was pretty much the same between the before and after.....

Sorry for the OT, great thread.

[DADx2]

I'm running a bottom mount SPA manifold, HTA3586R turbo @ ~24psi, big valves, CP pistons, Eagle rods, 11mm head studs, Cometic HG, ARP mains, 60 lb injectors, Technica tune.

[E36 HateR]

I was thinking about running a wastegate pipe to the back of the car, no more than 1.5 inches in diameter next to my straightpipe off the downpipe, might be overkill I guess.

[someguy2800]

I completely get where you are coming from....I love hot-lapping at the strip.

I've found the IRS vs Live axle thing being widely miss-understood from a perspect of how the chassis is loaded. The lifting action, what pulls the front tires into the air, on an IRS comes from the center of the car through the subframe. On a solid axle, it comes from where the 4 link or ladder bar is connected, which is usually about the same place. Our IRS places the thrust force on the outside of the chassis where the trailing arms connect, where a live axle is placing this force in close location to the lifting action. These forces are in different directions, working somewhat against each other at times. The closer you can put the input of these forces together, the more control you will have on them. On an IRS like ours, these forces are a couple of feet apart, and for the most part, working against each other through the chassis' sheet metal. A 4 link can be faster than an IRS because of how it can harness the power being applied through the chassis, not primarily because of how it plants the tires.

When I was building the 330Ci, we tied the trailing arm mounting points into the roll cage structure, along with the subframe mounting points for this very reason. I don't have any proof that it worked aside from running 2 tenths faster with 20 more HP and the car was 250 lbs heavier. There were a few other things that helped like a lighter flywheel, better clutch, and slightly higher gearing, but the MPH was pretty much the same between the before and after.....

Sorry for the OT, great thread.

Precisely. I didn't go into that reasoning as I assumed it would just start an argument with people that don't believe in physics. Once I started doing some reading into the science of drag car chassis tuning, it didn't take long to realize it is impossible for an IRS to ever perform as effectively as a live axle in a drag race environment. I personally think it facinating

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I was thinking about running a wastegate pipe to the back of the car, no more than 1.5 inches in diameter next to my straightpipe off the downpipe, might be overkill I guess.

they might quiet it down a little but not much. I guess it depends on how much noise is tolerable. I for one hate loud cars on the street.

[E36 HateR]

But you would only hear the dump tube when your on it.

Its not like its always loud all the time

[someguy2800]

too loud for me, even if its only under high boost.

[black bnr32]

Perry, how about you run an electronic exhaust cutout? power for the strip and silence for the street?

[someguy2800]

that would be good but I would just as rather not have the extra weight.

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I couldn't believe when I weighed the 3" full length exhaust on my old m20, allmost 50 lbs from the downpipe back.

[good & tight]

Make the exhaust out of aluminum to save the weight and not have the hassle of switch back and forth?

that would be good but I would just as rather not have the extra weight.

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I couldn't believe when I weighed the 3" full length exhaust on my old m20, allmost 50 lbs from the downpipe back.

[someguy2800]

Thats a good idea, I was planning on making the race exhaust out of 4" alluminum so now I am thinking of doing a mid pipe to a single muffler in the center of the car with a V band, so when i get to the track I can just quickly pull the muffler and replace with a short dump tube rather than swapping the whole exhaust system.

[hsvturbo]

Yesterday I was over at my friends shop having him machine a flange for me and he had boxes of V-band flanges made up of aluminum and stainless for this purpose. Funny thing is that it took him longer to draw up the flange and upload it to his CAM software then it took the machine to mill out the flange.

[someguy2800]

I havn't updated in awhile so I thought I should post up the progress.

I finally made up my mind about the exhaust. I will probably regret this the first time I start the car but I decided to get the sand out of my pussy and deal with some noise. I bought the aluminum tubing to build the exhaust and bought a hooker headers max flow 4" muffler. Its a very nice piece. If I can't stand it I may put another one inline. I also got a small 2" glasspack to put on the wastegate dump.



As for build progress, I am waiting on my mls to assemble the motor, but have pecked away abit at the car. I finished mounting the wastegate, which took way too much time due to me being picky about location. Also finished fabbing and welding in the bolt in plates for my core support. I cut the core support out to make pulling the motor easier and to make some intercooler room, so now I welded in some plates so I can bolt it in and out of the car. Should save alot of hassle pulling the motor all the time like I do. I also cut out the verticle supports that run from the core support to the frame stubs so I need to support this somehow as its so flimsy that the weight of the hood would fold it over. The plan is to use the intecooler as a structual member. The intercooler will bolt to the core support with a couple brackets on the top, and the bottom will bolt to a couple tabs on the frame stubs.

I wasted my entire saturday modifying my intercooler. I had a cheap cx racing intercooler for an evo 8, same kind I had in my old setup. The core is the perfect size for an e30 but the inlet and outlets are in the wrong spots so you have to cut them off and weld them back on. Unfortunately after hacking it all up to fit how I wanted I started welding it back together and found the alloy they used in the endtanks to be nearly unweldable. Its been awhile since I did much of it, but I have tig welded quite a bit of aluminum, and this was by far the worth thing I've ever tried to weld. It wouldn't fuse well and was full of contaminates and porosity. Every weld resulted in black soot on either side of the weld zone from burning the contamination out of the material. I wasn't comfortable that it was going to be safe so I decided to cut my losses. It was so brittle that I could actually chip the whole endtanks off in chunks with a hammer and throw them in the trash. You get what you pay for. So anyway I ordered a slightly smaller core vibrant intercooler that I'm hoping will fit behind the grill without having to modify anything. I have read some really awful things about the thermal efficiency of the ebay cores so mabey it will be a good thing after all. One more lesson in my life long process of learing that the cheap allways comes out expensive. In the money I've spent on these two intercooler I could have bought a garrett core and made my own. Mabey I'll learn someday.

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parts pile for this week



I spent tonight mounting up my plastic bumper swap. I've hear alot of people make a big deal out of how much work it is to do the plastic bumper swap on an e30 so I figured it would take quite a bit of time. Poeple always say you have to modify the sheet metal on the back of the car where the bumper shocks mount. I don't know what they are talking about because mine bolted right up, no modifications needed. The front ends of the rear bumper are too long so I just marked the ends with a sharpy and cut them off. most people try to sculpt them into fitting the fender opening just right but I found that you can just trim them so they mold into the fender flare rather than wrapping around it. way easier. It took me like 40 minutes start to finish.

[vollosso]

How does glasspack sound on a wastegate?

[someguy2800]

only one way to find out

[Robocop]

Did you get an early model e30 for better tire clearance?
On late model lower arches it's tough to fit some good meat without rakeing the hell out of it.

[someguy2800]

No I got an early model because it was the first e30 I ever saw in my life and it happen to be for sale. I bought the car when I was 17 and didn't know anything about them. the higher arches are just an added benefit. I actually have an excess of tire room. As the car sits now it has .5" spacers on each side and has a good 1 1/2 of room to the inside. If there was enough room for the driveshaft I could actually move the tires about an inch inward and drop the ride height another 2 inches or so before they would bottom out on the fenders. If I switched to a 275-50-15 radial I could slam the car at least 4 inches. For my purposes at the moment I want the car a bit high as it is for weight transfer.

[jsolares]

Love the thread, nice work on the car, can't wait to see how it turns out

[auaq]

Happy July 4th!



A present for someguy2800.

[someguy2800]

here is me touring a caterpillar workshop when I was in college. Its one of two off a V16 locomotive engine.



boring update

I got the new mounting plates welded onto the frame stubs. Looks much nicer now.



The grey piece is a 3d printed spacer I made to get mount the shock in the correct position




with the original ES valance



here is a tease of what it looks like with the 325es front spoiler on the plastic bumper. Took some triming to make it fit. I'll try to get some better pictures today.

[auaq]

But the one that I've got for you is even better for your E30! Anyways, why is the truck on those two pieces of wood?

[someguy2800]

I'm fairly certain it would crush the e30 flat. the wood blocks keeps rain from collecting in the bed. driveway doesn't have enough slope.

[auaq]

Ah, gotcha!

[Colby Colbs]

Happy 4th!

[someguy2800]

thanks you too colby

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test fit the driveshaft. Its a 4" OD used nascar sprint cup driveshaft with 1350 u joints. I got it for like $100 shipped. If you look around a bit you can get used nascar stuff for pennies. All circle track gearboxes use a 32 spline output shaft, but a T56 magnum is 31 spine so I had to get a new yoke. Its a billet chromoly yoke from Mark Williams Enterprises. Really nice piece.



When I was taking out the U joint I accidentally messed up one of the caps so I couldn't put the new yoke on the shaft but I mocked it up in the car anyway. Length is perfect. Plenty of clearance in the tunnel too.







Took some more or less random pictures while I was down there. enjoy.







fuel lines with 3d printed holders




the pinion flange is also chromoly from Strange Engineering.




this shows the custom ebrake cables. made by lokar specifically for the thunderbird brakes. There is a braked welded into the tunnel where the cables go into the car.



3d printed brake line and ebrake cable holder



the e brake cable loops over the back of the axle housing. I will probably ziptie both lines to the control arm.



clearance to the inside of the tire.