I am thinking about having another engine built for the M7. The current engine is nice, but at some point I'd like to move from keeping up with an E36 M3 to keeping up with an E46 M3. Here are the high level goals:
1. 300+ rwhp (at 233 rwhp right now)
2. reliability same as or close to stock (which is pretty darned good so far)
3. maintain some semblance of mid range torque, it's not a dedicated track car
4. no or minimal changes to current wiring harness
5. maintain S38B35 block since it fits without mods with the E23 engine mounts
Here are some ideas, please comment on the pros and cons:
a. increase engine size to somewhere between 3.7 to 3.9 liters. I've heard the 3.8s have some issues, but can't remember what they are.
b. Use a 264 or 272 cam? I remember seeing a dyno of an S38 engine with a 272 cam and it appeared to me that raising the redline to about 7500 would be useful since the engine peaked in the high 6k RPM (it's been a while since I saw the chart). If this is so, would new valve springs be necessary? Would it be worthwhile?
c. Lighter pistons and connecting rods?
d. M88 head? S38B35 head? S38B36/38 head?
e. What about using the B35 intake vs. B36 intake/MAF? How far will the current setup take me? Will I need to make major mods to the wiring harness to accomdate a B36 intake/MAF?
f. Is a 2 x 2.25 exhaust system adequate? Or is 2 x 2.5 better?
g. Should I junk the exhaust cam gear mod?
h. Is my goal of 300+ rwhp in conflict with any of the other constraints? If so, what might I have to give up?
Any other info you can provide would be helpful! I believe the Dinan 3.9 S38 engine was rated at 341 hp (not rwhp). Anybody heard of reliability or other problems with that setup? Did that use the 248 cam or 264?
Thanks,
Eric
[Edit by Eric Q on [TIME]1121911423[/TIME]]
Building a better s38
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Mark (Escondido, CA)
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Kenny Blankenship
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Guest
Eric,
I don't think you'll be able to achieve the RWHP numbers you're looking for. Assuming a maximum 20% drivetrain loss your proposed engine would have to make 375 HP for 300rwhp. That's a pretty high tall order in combination with keeping street drivability, minimal wiring changes, plus passing Cali SMOG. You might pull it off if you build a 3.9/4.0 stroker with 10.5:1 and the 272/264 or possibly a 280/272 cam configuration. The biggest hurdle I see is sourcing the crank. Dinan used a custom crank made by SCAT and these are rare as hens teeth. When a good one does show up for sale they are $$$$s. I believe that RD Sport in Europe also built a custom stroker crank, I've never seen pics of one, only read about it. Some time ago, someone tried to put together a group buy of SCAT stroker cranks. SCAT will do it, IIRC the deal fell through due to lack of serious, cash up front interest. Cost was something like $5k for each crank.
Another avenue to consider, a compromise of sorts. Build a high output engine and combine it with an aggressive weight loss program. I don't know how much of the uber luxury appointments your M7 still has in place, but it woulldn't be too far fetched to believe that 300#s couldn't be lost. That's about the weight difference between a typically equipped Euro E28 M5 and the US/NA version. Simply swapping out the heavy power comfort seats for a set of manual Recaro or similar seat would be worth about 200#.
Rich
I don't think you'll be able to achieve the RWHP numbers you're looking for. Assuming a maximum 20% drivetrain loss your proposed engine would have to make 375 HP for 300rwhp. That's a pretty high tall order in combination with keeping street drivability, minimal wiring changes, plus passing Cali SMOG. You might pull it off if you build a 3.9/4.0 stroker with 10.5:1 and the 272/264 or possibly a 280/272 cam configuration. The biggest hurdle I see is sourcing the crank. Dinan used a custom crank made by SCAT and these are rare as hens teeth. When a good one does show up for sale they are $$$$s. I believe that RD Sport in Europe also built a custom stroker crank, I've never seen pics of one, only read about it. Some time ago, someone tried to put together a group buy of SCAT stroker cranks. SCAT will do it, IIRC the deal fell through due to lack of serious, cash up front interest. Cost was something like $5k for each crank.
Another avenue to consider, a compromise of sorts. Build a high output engine and combine it with an aggressive weight loss program. I don't know how much of the uber luxury appointments your M7 still has in place, but it woulldn't be too far fetched to believe that 300#s couldn't be lost. That's about the weight difference between a typically equipped Euro E28 M5 and the US/NA version. Simply swapping out the heavy power comfort seats for a set of manual Recaro or similar seat would be worth about 200#.
Rich
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Adam W in MN
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Eric,
Just from what I've learned as a new E34 M5 3.8 liter owner, the 3.8's with the chip modification seem to do about 300-310 at the rear wheels. Of course this will violate your requirement to keep the S38b35 block in your car. Also I'm not sure what other ECU and other modifications are necessary to get a 3.8 in your car, if you could even find one (I bet they aren't cheap). I hear people on the E34 M5 message boards complaining about S38b38 reliability. I guess time will tell with mine, but I suspect these 3.8 liters were at the extreme end of the design BMW had intended and are not likely to tolerate a lot of abuse. I had the rod bearings replaced on mine as soon as I bought it and it was a good thing since they were in poor shape. The S38 guru mechanic here in Chicago (Ben Thongsai, CCA member, mechanic, S14 and S38 expert) said I probably would have spun a bearing soon if I hadn't changed the rod bearings. He suspected it was a combination of crappy gas, autobahn revs, and not letting the oil temp come up before romping on it. She S38b38's have thinner conn rod bearings than the other S38 motors so I think that is why they tend to fail sooner if not cared for. I religiously wait for the oil temps to come up in my M5 before having any fun.
So I don't know if that is the technical answer you're looking for, but it does provide some info to add to your collection. I think a chipped S38b36 motor will make close to what my motor makes stock so that could be an alternative. I would assume if you are willing to spend the money for the big valves that a 3.8 has, head work, and some tricks with the bottom end with lightweight pistons and conn rods as a possibility, you could achieve some very respectable numbers from your S38b35. It all comes down to .... how much do you want to spend?
Adam Wilson
www.e12m535i.com
Just from what I've learned as a new E34 M5 3.8 liter owner, the 3.8's with the chip modification seem to do about 300-310 at the rear wheels. Of course this will violate your requirement to keep the S38b35 block in your car. Also I'm not sure what other ECU and other modifications are necessary to get a 3.8 in your car, if you could even find one (I bet they aren't cheap). I hear people on the E34 M5 message boards complaining about S38b38 reliability. I guess time will tell with mine, but I suspect these 3.8 liters were at the extreme end of the design BMW had intended and are not likely to tolerate a lot of abuse. I had the rod bearings replaced on mine as soon as I bought it and it was a good thing since they were in poor shape. The S38 guru mechanic here in Chicago (Ben Thongsai, CCA member, mechanic, S14 and S38 expert) said I probably would have spun a bearing soon if I hadn't changed the rod bearings. He suspected it was a combination of crappy gas, autobahn revs, and not letting the oil temp come up before romping on it. She S38b38's have thinner conn rod bearings than the other S38 motors so I think that is why they tend to fail sooner if not cared for. I religiously wait for the oil temps to come up in my M5 before having any fun.
So I don't know if that is the technical answer you're looking for, but it does provide some info to add to your collection. I think a chipped S38b36 motor will make close to what my motor makes stock so that could be an alternative. I would assume if you are willing to spend the money for the big valves that a 3.8 has, head work, and some tricks with the bottom end with lightweight pistons and conn rods as a possibility, you could achieve some very respectable numbers from your S38b35. It all comes down to .... how much do you want to spend?
Adam Wilson
www.e12m535i.com
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Kenny Blankenship
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The 300 rwhp is a goal, but not absolute. I was figuring about 350 crank hp considering 15% drivetrain losses. I also figure 272 is the max I can go on cams in order to have a chance at passing smog. Sounds like I might have to limit the engine size to 3.6-3.7?
How much do I want to spend? I've heard the stock S38 rebuild is $12-$15k. Maybe a couple thousand more for the niceties? If could get an S38 long block fairly cheap, have it built, and then sell the one that's in my car, maybe I could save a little bit. But I want to do it once and do it right.
How much do I want to spend? I've heard the stock S38 rebuild is $12-$15k. Maybe a couple thousand more for the niceties? If could get an S38 long block fairly cheap, have it built, and then sell the one that's in my car, maybe I could save a little bit. But I want to do it once and do it right.
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Bryan in SB
- Posts: 2002
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Of course.
Look, i figure we've got 20 years, tops, left before the gasoline combustion engine becomes an anachronism / illegal for personal transportation in this country. I don't know why you people are _wasting_ these years in car-law shitholes like california
The golden era of HP wars we're in right now is going to come crashing down and will be backed up with legislation to ensure nobody ever enjoys themselves again. And older cars will be hit hardest.
In any case, in ND, when you title a vehicle, they ask you how many axles it has, and how long you've been driving it on ND roadways. That determines the vehicle registration cost, and then they hand you plates, and thats that
Look, i figure we've got 20 years, tops, left before the gasoline combustion engine becomes an anachronism / illegal for personal transportation in this country. I don't know why you people are _wasting_ these years in car-law shitholes like california
The golden era of HP wars we're in right now is going to come crashing down and will be backed up with legislation to ensure nobody ever enjoys themselves again. And older cars will be hit hardest.
In any case, in ND, when you title a vehicle, they ask you how many axles it has, and how long you've been driving it on ND roadways. That determines the vehicle registration cost, and then they hand you plates, and thats that
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Guest
How much do I want to spend? I've heard the stock S38 rebuild is $12-$15k.
There's no reason an S38 rebuild should cost that kind of money. The last time I looked at the MM website, I recall a number something like $8995 for a stock S38 rebuild.
Rich
[Edit by Rich Euro M5 on [TIME]1122088284[/TIME]]
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Kenny Blankenship
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It's called "good weather". I have a bit of an aversion to snow.Look, i figure we've got 20 years, tops, left before the gasoline combustion engine becomes an anachronism / illegal for personal transportation in this country. I don't know why you people are _wasting_ these years in car-law shitholes like california
Besides, exactly how many Chinese people are there in North Dakota??? :p
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Guest
[QUOTE="Matt"]I don't see how anyone could possibly have a snow aversion with Quattro's and 325iX's being so cheap these days.
The way i see it, i get 6 track months, and 6 rally months.[/QUOTE]
Matt,
If you were to move away from "The Great White North" for an extended period of time ,to say San Diego. You too would probably develop the same affliction Eric suffers.
I also have the same disease as Eric and I spent many years of my youth living in the snow belt.
The real reason I posted though, you didn't answer Eric's other question. Inquiring minds want to know.
:p
Rich
P.S. How's the M5 run on studded tires ??
The way i see it, i get 6 track months, and 6 rally months.
[/QUOTE]Matt,
If you were to move away from "The Great White North" for an extended period of time ,to say San Diego. You too would probably develop the same affliction Eric suffers.
I also have the same disease as Eric and I spent many years of my youth living in the snow belt.
The real reason I posted though, you didn't answer Eric's other question. Inquiring minds want to know.
:p
Rich
P.S. How's the M5 run on studded tires ??
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stuartinmn
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- Location: Minneapolis
Hmm...I got curious myself about that question so I did a Google search on "Fargo Chinese."
I found this page, which says there are about 300 Chinese people in Fargo, mainly students at NDSU.
http://www.ndsu.edu/International/int_s ... hina.shtml
I found this page, which says there are about 300 Chinese people in Fargo, mainly students at NDSU.
http://www.ndsu.edu/International/int_s ... hina.shtml
I have no idea how the M5 is on studded tires, as it is garaged from Nov to April.
My Audi has twice the drive wheels and half the horsepower.
And, if some shit-brain runs into the Audi in their rwd pickup with dry-rotted bias ply tyres because they don't even bother tapping the brakes before coasting through red lights, a peice of BMW history hasn't been destroyed.
I used to live in seattle, and then voluntarily moved to Fargo. I just spent the last 9 days back in seattle for work and I only miss it a little.
[not that seattle qualifies as "good weather"]
My Audi has twice the drive wheels and half the horsepower.
And, if some shit-brain runs into the Audi in their rwd pickup with dry-rotted bias ply tyres because they don't even bother tapping the brakes before coasting through red lights, a peice of BMW history hasn't been destroyed.
I used to live in seattle, and then voluntarily moved to Fargo. I just spent the last 9 days back in seattle for work and I only miss it a little.
[not that seattle qualifies as "good weather"
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Kenny Blankenship
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Rich and Stuart, you guys crack me up!!! I do like good food, Chinese, Japanese, Indian, Filipino, Italian, French, Korean, Seafood, Mexican, Ethiopean, Jamaican, etc... Try finding all THAT in Fargo.
Anyway, back to the subject...Do you think it would help if I used an M88 head on the S38 bottom? Or use a complete M88 engine to rebuild?
[Edit by Eric Q on [TIME]1122352078[/TIME]]
I do like good food, Chinese, Japanese, Indian, Filipino, Italian, French, Korean, Seafood, Mexican, Ethiopean, Jamaican, etc... Try finding all THAT in Fargo.Anyway, back to the subject...Do you think it would help if I used an M88 head on the S38 bottom? Or use a complete M88 engine to rebuild?
[Edit by Eric Q on [TIME]1122352078[/TIME]]
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Guest
S38 with Euro Chip and Exhaust will easily give you 300 RWHP. Below link will show the Dyno chart of my Euro 3.8 M5.
http://members.cox.net/euro-m5/m5-37.jpg
http://members.cox.net/euro-m5/
Carl Nelson in La Jolla (La Jolla Independent) has dropped in a S38 in his 1985 Euro E28 M5. Hopefully he'll complete the wiring and get it running. I will definitely check it out to see how it feels.
http://members.cox.net/euro-m5/m5-37.jpg
http://members.cox.net/euro-m5/
Carl Nelson in La Jolla (La Jolla Independent) has dropped in a S38 in his 1985 Euro E28 M5. Hopefully he'll complete the wiring and get it running. I will definitely check it out to see how it feels.
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Guest
[QUOTE="Euro-M5"]S38 with Euro Chip and Exhaust will easily give you 300 RWHP.
[/QUOTE]
[QUOTE="Mike K"]Just curious, but are these results with the euro headers? Would the Euro chip be beneficial running the US headers and Fahey pipe (no cats)?[/QUOTE]
Mike,
Go to the secodn link and you'll see that this +300RWHP result is from a Euro E34 M5 with the S38B38 engine. I don't recall all the differences off the top of my head but here's a few things that come to mind.
Displacement 3.8L
Compression 10.? : 1
Camshafts IIRC 264 degree
Factory MAF
Much more sophisticated Motronic
Rich
[/QUOTE]
[QUOTE="Mike K"]Just curious, but are these results with the euro headers? Would the Euro chip be beneficial running the US headers and Fahey pipe (no cats)?[/QUOTE]
Mike,
Go to the secodn link and you'll see that this +300RWHP result is from a Euro E34 M5 with the S38B38 engine. I don't recall all the differences off the top of my head but here's a few things that come to mind.
Displacement 3.8L
Compression 10.? : 1
Camshafts IIRC 264 degree
Factory MAF
Much more sophisticated Motronic
Rich
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scottiesharpe
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- Contact:
Eric, if you are not going to pressurize the intake, then there is no substitute for displacement. Either make the combustion chamber bigger, or squeeze more air in there with higher compression - or both!
The M88 was listed at 285hp stock right?
I'm running the M88 with a racing dynamics chip and a B&B exhaust. It really runs great. Later this summer, Bruce is going to make me a track pipe so I can put the stock cat in a glass case (only to be removed for smog testing!), then I will readjust the mixture and we'll take the car to the dyno to see what it puts out.
My guess is 300hp - 315hp crank.
The M88 was listed at 285hp stock right?
I'm running the M88 with a racing dynamics chip and a B&B exhaust. It really runs great. Later this summer, Bruce is going to make me a track pipe so I can put the stock cat in a glass case (only to be removed for smog testing!), then I will readjust the mixture and we'll take the car to the dyno to see what it puts out.
My guess is 300hp - 315hp crank.