Messages

1

Swaps, Turbos, Buildups / Re: JRW'S 91 318is turbo build

« on: April 08, 2016, 03:03:48 PM »

There is no way the stock manifold is a weak link around 300hp on a turbo engine. Where would the restriction be?

The general design could hamper flow at the top end. As I stated, it's what I've heard from 2 separate people who have themselves done the whole 300whp thing before. I have no way of verifying it, short of building a custom manifold and doing back to back dyno runs I could not be sure, but given the design of the manifold, it seems reasonable. I have a turbo and a fuel system that's easily capable of it but I still don't have a TIG welder so we'll see if I'm able to break 300whp with a stock manifold, I will certainly post my findings if I do.

2

Engine + Driveline / Re: compression ratio

« on: January 29, 2016, 08:48:46 AM »

I have been able to get results that make sense and fit what I've read about the stock stuff with this calculator: http://www.csgnetwork.com/compcalc.html

Using the following figures, some of which I found searching this forum.
Bore: 84
Stroke: 81
HG Bore: 85
Compressed HG: 1.73mm
Combustion chamber volume: 33.5cc
Piston dish volume(negative is dish): -7.4cc
Piston above deck height (negative is proud): -0.15mm

These figures yield a result of 9.99:1

Adding my .120" (3.05mm) MLS head gasket I get a not-exactly-what-I-wanted figure of 8.8:1. Based on this I'm considering buying and installing a 0.098" (2.49mm) MLS to bring my compression ratio up to 9.3:1, hoping for a significant increase in responsiveness and low end/spool.

If someone can chime in with verified figures, especially piston height and CC measurements, it would be much appreciated. I do not have access to a spare M42 to perform this on. The head gasket firgures are taken directly from my removed stock head gasket, however, I am measuring with harbor freight calipers, getting different measurements depending on where I measure and am not sure how much the head gasket grows when it is un-clamped.

(edit)
for future reference, I found someone's measurement of the combustion chamber at 27cc
still no consensus

3

Swaps, Turbos, Buildups / Re: JRW'S 91 318is turbo build

« on: January 28, 2016, 10:44:53 PM »

Interesting intake manifold. I have been searching out design options for an upgraded intake manifold for my Turbo M42, since I've heard from multiple people that it becomes a weak link in the flow path around 300bhp, I can't weld aluminum though, which is a problem.

4

Swaps, Turbos, Buildups / Turbo M42 intake manifolds

« on: December 25, 2015, 09:10:19 PM »

I have read, from a couple of people who have done it, that the stock M42 intake does not flow well enough to make more than 280 or so whp easily. In my reading about of some of the more powerful M42 builds I have seen some nice custom intake setups, and some designs that are known to look better than they perform (such as angled throttle body, sheet metal box intakes).

What have those of you who have high-power (let's say over 300whp) turbo M42s have done about the intake manifold?

I'm gathering ideas to fabricate my own intake manifold so I can make more power once I install my next turbo. I'd prefer to use the stock lower intake manifold section to reduce expense, even if it involves cutting the flange off. A thread like this could become a valuable repository of knowledge for future turbo M42 builders if people with experience share.

5

Engine + Driveline / Re: IDIOTIC MISTAKE - Sheared Top of Hex Nut for Timing Tensioner Piston

« on: November 23, 2015, 03:54:53 PM »

Probably. You're unlikely to be able to get it out with the timing cover on the engine. Looks like it's time to pull it off and since that's a pain, you may as well replace everything you can afford to replace behind it.

6

Swaps, Turbos, Buildups / Re: Your ideal build.

« on: November 18, 2015, 09:06:22 AM »

The final tally......212HP and 172ft/lbs at the crank in a 2045cc motor. That's US E30M3 territory, stock (192HP/177ft/lbs) and chipped (216HP/177ft/lbs) in a 2302cc motor. Figures are all Dyno Jet #'s

Impressive.

7

Swaps, Turbos, Buildups / Re: m42/m44 stock manifold turbo adapter

« on: November 18, 2015, 08:12:52 AM »

I was going to weld up an adapter for the stock header, but there is not enough space for a good setup under the hood. I'd like to see one that fit well, but the only one I saw had the turbo mounted low and no AC.

8

Engine + Driveline / Re: compression ratio

« on: September 24, 2015, 12:22:56 PM »

Your calcs are pretty good. I have a spread sheet I use from real measurements. OEM is 9.94:1. Decking the piston 1.65mm gives 8.56:1.

So your 1.7mm was pretty much on the money.

Note: My calc (and yours) assumes you maintain the piston dish cc which isn't true if you just skim the piston.
The dish is 3.5mm at its deepest leaving you with some dish after skimming but not the full 7.4cc and therefore a higher CR when taking into account the changing volume sizes. For your calc to work you must maintain the original dish volume.

Would you mind sharing that spreadsheet? I'm still wondering exactly what my CR is with the .120" head gasket.

9

Engine + Driveline / Re: metal or paper timing case gasket?

« on: September 24, 2015, 12:14:10 PM »

Makes me wish I had been able to find an idler-free timing case to put on my M42 when I had it apart.

10

Engine + Driveline / Re: Another not starting after M42 swap thread...

« on: August 26, 2015, 08:45:52 AM »

Make sure spark plug wires/coil on plug units are in the right place, make sure your cam and crank position sensors are plugged in right.

11

Swaps, Turbos, Buildups / Re: Running M44 build!

« on: August 22, 2015, 07:21:46 PM »

Cool build! What are your plans for it? ITBs? Or just faster-than-it-was-stock NA street car?

I used the head and headgasket cc numbers in this thread to satisfy my curiosity for my real compression numbers, played with the calculator until I got it to say ~10:1 with the stock numbers, which left me with 8cc for the stock pistons, FWIW. Came out to 8.7:1 compression ratio with the .120" headgasket, a little lower than I would want ideally, maybe I should've picked the .098" one, but I didn't have this info when I bought it. The engine has held  up and doesn't ping too terribly easily so I'm not complaining. A .3 static difference probably doesn't mean all that much for my use.
I used:
Bore: 84mm
Stroke: 81mm
HG Bore: 86mm
Compress HG: 1.6mm
Combustion Chamber: 33cc
Piston volume: 9cc
Piston deck clearance (Above): 0.15mm

12

Suspension / Re: building your own coilover options

« on: August 18, 2015, 09:33:20 PM »

I'm building coilovers soon. I have the parts but I'm too swamped with maths at the moment to work on my car so I'm driving around on stock springs and freshly blown front struts

I got some generic adjusters intended for Hondas on eBay, bought Koni SAs on TireRack (on sale!), and got 450lb 6" front springs and 650lb 5" rear springs. I did a lot of research and concluded that with springs of that rate and length I'll be able to maintain a good ride height (1" or less below than stock) and seriously improve handling for my purposes (street and autox). I will be keeping the stock swaybars. It may be a little stiff for most, but I prefer a stiff, controlled ride because motorcycles spoil you like that. I have driven a car with the H&R sport/bilstein sport combo and it was nice for a street car, but I found it a little soft. Keep in mind that most good setups put the rear springs at  1.4-2x the rate of the front springs. This is due to the suspension geometry, which alters the effective rear rate quite drastically!

You can get some helper springs if 6" are too loose in the front for your tastes, but if you use helpers in the rear, they must be welded to the main spring, otherwise they can just fly out at full droop due to the spring configuration.
 FWIW, the static height of the stock rear spring on my car is 5-3/8"

I got my rear springs here: http://www.racingsprings.com/
They have a pretty good selection, but I found my fronts on clearance elsewhere and saved some $$. If your budget is better than mine, I would recommend buying Ground Control's coilover conversion kit, which has higher quality adjusters, and comes with ground control's support, warranty and assistance in making your spring rate choice. http://www.ground-control-store.com/products/description.php/II=121/CA=241

13

Swaps, Turbos, Buildups / Re: oil feed for turbo

« on: August 18, 2015, 09:15:04 PM »

I used the spare port on the back of the head.

14

General Topics / Re: A/C quantities

« on: July 15, 2015, 08:16:00 PM »

According to the Bentley manual, 975g (2.1lbs) of R12, 200cc of oil, back of the compressor on my '91 318is specifies "Denso Oil-6." I don't know what the equivalent viscosity  for that is in mineral oil, but when I did my R134A conversion recently I used ISO46 oil.

From what I've seen put an ounce of oil in the condenser, an ounce in the drier, and the remainder in the compressor. It would be worth your while to have the system flushed professionally or at least buy a pressurized flush-in-a-can, it's difficult to get all of the old crud out of the system, especially if someone before you used stop-leak. Ask me how I know.

15

Engine management / Re: Could this be causing some of my problems?

« on: January 20, 2015, 08:13:13 PM »

Thanks. I recently replaced my ICV so maybe I lost the plug when I was fiddling with the intake boot. Do you think that it is sucking in unmetered air and could cause any issues?

Sucking in unmetered air would cause the engine to run poorly.