Stroking the E30

[WAKman]

thinking about this:

https://metricmechanic.com/baby-six-m20-engines/

maybe just paying for the completed engine is the easiest... plus MO is driving distance for me.

That's about what I have in this engine. But . . . do you really want to miss out on the type of entertainment I had?

[WAKman]

IMO that isn't enough power to go with a 3.25 diff when paired with a G260 trans.

Power seems pretty good. Some of the pics are missing.

The car came with a 3.25, which the old tired engine had real problems satisfying, so I added the 4.10 LSD.

I take multi-thousand-mile road trips in my cars every year, and I'd put the 3.25 back in just for that. Last year I drove my 02 Boxster S 4,000 miles, down the coast from Seattle, across to Phoenix, and back up through Arizona, Utah, and Idaho. It was epic. Here we are on the rim of the Grand Canyon.



In a couple weeks I'll be team-driving from DC to Washington State, alas in a Jeep Wrangler and a Ford F150, helping family move. But the E30 will get the nod later in the summer if I can find the time. One of the big reasons I stuck with the M20 instead of a swap was my desire to retain the factory A/C and the factory look. Plus I love the M20.

[WAKman]

Pics on the cam mark didnt show..

Curious - would you deal with bimmerheads again?

Im debating on how to approach this.. my ol girl has 320,000 miles and I have a few blocks and a few heads..

I'm pretty happy with how this combo worked out. Bimmerheads was fine--they sent the wrong pistons the first time, but made up for it by sending the replacement CPs, which were more expensive, and picked up all shipping.

[Digitalwave]

Why is that not enough power? Not enough power down low for the 3.25?

Just my opinion from a performance perspective. I guess if it's a car doing thousand mile road trips you'd want a really long gear like that.

[moatilliatta]

I have 275whp and I consider 25lbs weight penalty for a 6th gear and go 3.64..

But the 3.25 is the best compromise with cruising on the highway. Agreeing by one who also put the miles on them. I guess also I'm 1:1 filth..

Not much off the shelf 3.25 - 3.73, Minus Z3 diff 3.45, torsion or clutch pack$


I guess better than having it all together and wondering why it makes no tq with low compression... Glad to hear your machine shop caught that. AND! glad those CP pistons fit the slugs that were already punched!

[varg]

Car looks nice, probably drives nicely too with good NA torque. Dyno plot looks suspect though. Peak torque at 4,308pm and peak power at 5,251? Was that with the cam timing off? Seems early for a 274 cam, I would expect peak torque closer to 5,000 and peak power closer to 6,000 with that combo. What's the compression ratio?

IMO that isn't enough power to go with a 3.25 diff when paired with a G260 trans.

I agree, because I have a 3.25 and a turbo. I think the car would be sluggish at 210lbft at 4,300rpm. It is an ideal ratio for an E30 that will see highway miles provided it has the mid range torque for it.

[digger]

thinking about this:

https://metricmechanic.com/baby-six-m20-engines/

maybe just paying for the completed engine is the easiest... plus MO is driving distance for me.

Easiest is not the best though. I would piece together your own bits. Its more enjoyable that way and with some research or asking questions here you will end up with a better outcome IMO.

For headwork forced firebird is your best bet, actual port development work and verfied as improved using flow testing equipment.

Dyno plot looks suspect though. Peak torque at 4,308pm and peak power at 5,251? Was that with the cam timing off? Seems early for a 274 cam, I would expect peak torque closer to 5,000 and peak power closer to 6,000 with that combo. What's the compression ratio?

+1

[digger]

About a year ago, I decided to build a 2.9L stroker to relieve the wheezing 245-k mile factory engine in my 1989 E30. As far as I could tell, the engine had never been apart--I have records back to new through six (!) meticulous owners, showing lots of service and repairs, but no mention of an engine rebuild. Plus it still had the failure-prone head bolts, which was another indication of its virginity, as those would almost certainly have been replaced. But it was a really tired, high-mile virgin.

Since I wanted to keep the car drive-able and didn't care about numbers matching (maybe this will one day matter for E30s, but I hope not), I found a give-away engine nearby, brought it home, took it apart, and took the block and head to my machinist, Chuck (C&D Machine, Kirkland WA--highly recommended), along with a Bimmerheads 2.9 stroker kit. The kit contained an S52 crank, Molnar forged rods, 86mm Ross pistons, and ARP fasteners. I dropped everything off in December 2021. Thus began an odyssey.

The free engine was worth every cent I paid for it--a few days after drop off, Chuck called to say the block was junk. The next day, he reported that the head was also junk. I found another block that turned put to be usable at a friend's shop, but I had to go through five (!) cylinder heads to find one that was usable. Three had cracks, and one had been machined at an angle other than 90 degrees to the block, so the head rode higher at the front than the back. Number five was the charm--after I spent most of January hunting down every 885 cylinder head in the PNW, shelling out hundred dollar bills like chicken feed.

Some time in February, Chuck called to report that the pistons sat too low in the cylinders at TDC. I called Bimmerheads, and they said they'd had some problems with the sizes of the Ross pistons, and that they had switched to CPs (Carrillo). They sent me these as a replacement set and I returned the Ross set to them. Chuck confirmed that they fit, but we had already burned about two months dealing with broken or non-fitting parts. Nonetheless, I got all the stuff back by March--an assembled short block, and a ported head with a 274 Bimmerheads cam (reportedly made for them by Ireland).

Spring and early summer got filled with putting the rest of the engine together and sourcing the Megasquirt, injectors, and ancillary pieces, but I finally pulled the old virgin late summer and dropped in the new engine in October. I then had to make a make/buy decision. Since I had zero experience programming a Megasquirt and would be firing-up a new engine with a green cam that had been gobbling big wads of cash, I went the buy route and hired out this job to Patrick at Midnight Motorsports in Seattle (highly recommended). Shortly before Thanksgiving, I watched as Patrick fired up the car on his own Megasquirt tune running in the cam for 20 minutes. He broke the engine in over the next few days, street-tuning the motor via laptop. His goal was to provide a conservative street tune I could use for break-in mies, after which I'd get a power-tune on a dyno. I picked the car up and was pretty happy with how it ran, though I was instructed to be gentle for the next thousand miles, changing out the break-in oil at 250 miles and doing another change at 1000. The car felt very torquey and strong up through about 4.5k rpm, at which point the car stumbled, but I attributed this to the conservative street tune that we'd sort out at the dyno.

I was wrong . . . [to be continued]

maybe you can clarify if you have a 2.9L or 3.1L? S52 crank + 86mm = 3,123cc

why was the first block junk?

as others have stated the 3.25 is too long, 3.46 absoluate longest but a 3.73 or 3.64 cruises nice enough with 0.81 5th. I have done 10's of thousands highway miles with a 3.91 and with a fresh smooth engine and non obnoxious exhaust it is no issues.

[WAKman]

Thanks to all for the opinions and comments, especially on the power curves and gear ratios. This site is a terrific resource. I frankly stopped coming here for awhile because it seemed not to have a great deal of activity, and it was really hard to upload photos, but things seem to have improved quite a bit on both fronts, which is great.

So: there have been some interesting recent developments that may have a significant effect on things. Shortly after the new engine went in, with the break-in tune, the car had an occasional hot-start problem. I attributed this to gremlins in the tune that we'd straighten out at the dyno. After the dyno tuner did a series of full-throttle pulls that got the car fully hot and bothered, it stopped wanting to run at idle. We let it sit for about half an hour, after which it fired up just fine, but he had to set the idle at 1k for it to remain happy.

I've driven it a couple hundred miles since then, and it has run very well, but the hot start problem has gotten worse, causing some embarrassment at a gas station stop. In my experience, hot start problems can mutate into no-start problems pretty quickly. Time to dive in.

There's an old adage that in a no-start condition, as between the spark and the fuel, check the spark first. Then, check the spark again. So I checked for spark by pulling a plug lead, clamping a test spark plug between my teeth and . . . OK, I didn't do it that way. Anyway, the spark looked kind of weak--yellow instead of blue, perhaps a bit erratic. I checked the coil circuits and found them to be 0.7 ohms primary and 5,500 ohms secondary, versus the factory spec of .5 primary and 5,000 secondary, which was barely outside of spec, but I replaced the 245-k mile coil anyway. No start. I replaced the fuel pump and main relays with new ones. No start.

On the ignition side, that pretty much left the crank position sensor, which I checked last because I replaced it back in 2020 when I first got the car and did the timing belt and water pump. Factory spec is 540 ohms plus or minus 54 ohms. Mine read, at various times, 847 ohms cold start (it started right up) and 925 ohms hot, at which point it would not restart. I understand that resistance readings alone may not tell the whole story, in that even a unit having within-spec readings may still be bad, but these are significantly out of spec in any event, so I ordered a new one.

The problem with the crank position sensor is that it pretty much requires draining the coolant so you can take off the cooling hoses, cooling crossover pipe, and the distributor cap so you can get down to where the sensor wire crosses the timing cover and pull it out. Someone here may respond that you don't need to do all this to remove the sensor, but I couldn't figure one out, and anyway, I find that taking shortcuts often results in me spending a lot of extra time before inevitably doing the whole job over again the long way. My last effort to take a short cut resulted in a punctured radiator. Ouch.

And, I just finished draining and replacing the coolant for the timing belt fix last week. Aargh. So I pulled the whole thing apart this morning, spilling most of the coolant onto the garage floor, despite placing the bucket in what I thought was the absolute perfect place. It was not. As it turned out, pretty much the only thing that didn't get wet was the bucket.



I write, I am awaiting delivery of the new crank position sensor, so I will possibly have it all back together in the next day or two. Assuming it is the crank sensor and I get it back to running, I'm wondering the extent to which the faulty sensor affected power delivery in the dyno testing. Since I'm already planning a return to the rollers, it will be interesting to see the effects. After that, I plan to spend the summer driving the car through the PNW mountains.

The next big mod will be the installation of the RPD individual throttle bodies I have lying in wait.

[WAKman]

maybe you can clarify if you have a 2.9L or 3.1L? S52 crank + 86mm = 3,123cc

why was the first block junk?

as others have stated the 3.25 is too long, 3.46 absoluate longest but a 3.73 or 3.64 cruises nice enough with 0.81 5th. I have done 10's of thousands highway miles with a 3.91 and with a fresh smooth engine and non obnoxious exhaust it is no issues.

I may have misstated the crank's source motor. The Bimmerheads site is kind of vague on where it comes from. But the displacement is 2.9, and the compression ratio is 10:1.

The first block had a crack between the water jackets.

I actually don't mind the 4.10s for occasional highway driving. I tend to cruise about 70-75, at which it's turning about 3200-3400. It's pretty happy there. Around town, it's fun to have the 4.10s; I just have to use a gear higher than usual.

[Panici]

Thanks to all for the opinions and comments, especially on the power curves and gear ratios. This site is a terrific resource. I frankly stopped coming here for awhile because it seemed not to have a great deal of activity, and it was really hard to upload photos, but things seem to have improved quite a bit on both fronts, which is great.
...
I am awaiting delivery of the new crank position sensor, so I will possibly have it all back together in the next day or two. Assuming it is the crank sensor and I get it back to running, I'm wondering the extent to which the faulty sensor affected power delivery in the dyno testing. Since I'm already planning a return to the rollers, it will be interesting to see the effects. After that, I plan to spend the summer driving the car through the PNW mountains.

Things have definitely picked up around here. I love engaging with an active community of fellow enthusiasts!

Hopefully that crank sensor does it. Interested to see if there will be any difference at the dyno as well. (Does a weaker spark makes less power?)

PNW mountains sound lovely, it's on my bucket list to visit.

[WAKman]

The E30 continues to defy my efforts to fix its hot-start problem. The crank sensor was not the problem.

Getting around to something I should have done much earlier, I finally bought an inline spark tester, and have been able to determine that there is spark when hot cranking. So it's somewhere in the fuel system. Since the car has a bunch of miles, I decided to replace the fuel pump, on the off chance it was having trouble pumping when hot. Did the filter while I was at it. The car fired right up, we went for a zesty drive, came back, shut off hot, and . . . no start.

On a whim, I decided to check and clean the grounds. When I took the car apart, the chassis to engine ground strap was attached to a lug on the power steering pump. Knowing no better, I put it back together that way. Yesterday, though, I discovered through perusing the interwebs that it is supposed to be attached to the oil sump. Aha! I made this change, the car fired right up, we went for a zesty drive, came back, shut off hot, and . . . no start.

OK--we have spark, hot or cold. So, I figure the injectors are, for some reason, deciding not to fire during a hot restart. I watched a couple videos on YouTube where folks pulled the injectors and harness, then cranked the engine to see if they sprayed, usually pulling power with an alligator clip from a nearby 12v source, which yields an amusing arc of sparks. This looks to me like an excellent way to join the Jay Leno Burn Club, so I'll probably use the procedure in the Bentley Manual when/if I check the injectors. But I doubt they are faulty--they are brand new with this build, and if one or two were bad, I don't think it would cause the complete no-start no-burp situation when the engine is hot.

I took a look at the notorious C191 connector at the bottom of the harness, and it seems fine, without obvious signs of corrosion either on the plug pins or under the rubber boot. Since I happened to have a spare injector harness, I did a little investigating to check continuity and figure out which of the seven pins did what. Since the injectors are batch fired, pins 5 and 7 are connected to injectors 1, 3, and 5, while pins 5 and 6 are connected to injectors 2, 4, and 6, as shown by the attached hieroglyphic.



Hmm. This means that pin 5 provides the ground for each injector, so a heat-induced break in continuity as to pin 5 could disable all six injectors. So today I'll install the spare harness and see if that fixes things.

If any of youse have any suggestions I haven't though of, please let me know, as this problem is causing me to question reality and mourn the futility of life.

[digger]

you haven’t really described the hot start issue in detail.
When the engine is hot and you shut it off does it immediately have issues or does it need to sit for 10 min etc?
Does it crank and never start until it completely cools or just cranks excessively before eventually starting or something else?
Has it always done this or is it new and since what point in time?
I wouldn’t assume injectors are good. I would borrow a known good set for testing on the car.

[WAKman]

When hot, the car will crank but not start. Most times there is a brief sputter on the first try, then nothing but cranking. I then have to wait until the temp gauge is down to about halfway between straight up and cold before it will refire--about 10 minutes. The phenomenon is new since the build. When the car is running the injectors click away merrily.

Today I swapped out the injector harness. No change.

[McGyver]

How long are you cranking after the brief sputter?

Did you hook up a fuel pressure tester to see how much pressure you have in the rail?