Thinking about a rebuild with FI in mind

[Rich in WI]

I'm getting an itch to rebuild my engine and start rolling on the turbo project. I've got an oil leak at the front of the cylinder head (not too bad) so my brain is moving to grand plans. I'm wondering if there are any standard rebuild kits out there that might be useful (Todd?).

I'm looking at doing the following:
1) New oil pump
2) Beefy head gasket
3) Head studs
4) New timing components (sprocket, chain, etc.)

Obviously the standard rebuild stuff that may or may not need to be done would be done, too. Am I missing anything? I'm probably going to use new bearings in the bottom end and re-ring as needed.

One of my questions deals with my cylinder head. I've got a Hartge head with a 282 cam. Seems like the head would be a good thing for FI, but that the 282 cam would not. I've got a very slightly used 264 cam in my old cylinder head sitting in the garage. There would be some time between the engine rebuild and the implementation of a TCD kit. Absent FI, how will the Hartge head behave with a 264 cam? I figure it'll be similar to a B35 head and shouldn't be a big deal, but I'm not 100% sure on this.

Any thoughts are appreciated!

Rich in WI

[T_C_D]

Sounds like a solid plan. The 264 cam in the Hartge head will work well.
Todd

[Skeen]

Just talk to the Parts Pimp about the rebuild stuff. I don't know what you mean by "re-ring as needed," but I would go ahead and do all of them if you're doing any.

[russc]

While the 264 cam is fine for low end torque, what are you looking for power wise. Are you seeking a good street feel with the higher mid torque band, or more of a top end power car, that feels more like a E34 ///M5 on steroids? That 282 cam will work fine, but sacrafice some low end torque for high rpm power. I would personaly stay withe the 282 w/Harge head. But I like the feel of a car that pulls hard all the way to 6krpm.

RussC

[rundatrack]

Still having felt the power of a turbo m30.....*throws self on ground and sobbing*

!@#$ !@#$ !@#$ !@#$ !@#$

Hope isnt lost ~_~

[T_C_D]

[QUOTE="russc"]While the 264 cam is fine for low end torque, what are you looking for power wise. Are you seeking a good street feel with the higher mid torque band, or more of a top end power car, that feels more like a E34 ///M5 on steroids? That 282 cam will work fine, but sacrafice some low end torque for high rpm power. I would personaly stay withe the 282 w/Harge head. But I like the feel of a car that pulls hard all the way to 6krpm.

RussC[/QUOTE]

I don't think this is accurate Russ. The 270 cam in the 745i killed the torque and added lag. The 282 would be even worse. I really prefer the 260 cam that makes huge torque. The 264 is a good compromise. The 270 is NOT good for a mild street car in my opinion.

I really prefer the feel of the 260 cam over the 270 cam in the 745i!

Todd

[russc]

[QUOTE="russc"]While the 264 cam is fine for low end torque, what are you looking for power wise. Are you seeking a good street feel with the higher mid torque band, or more of a top end power car, that feels more like a E34 ///M5 on steroids? That 282 cam will work fine, but sacrafice some low end torque for high rpm power. I would personaly stay withe the 282 w/Harge head. But I like the feel of a car that pulls hard all the way to 6krpm.

RussC[/QUOTE]

[QUOTE="TCD"]I don't think this is accurate Russ. The 270 cam in the 745i killed the torque and added lag. The 282 would be even worse. I really prefer the 260 cam that makes huge torque. The 264 is a good compromise. The 270 is NOT good for a mild street car in my opinion.

I really prefer the feel of the 260 cam over the 270 cam in the 745i!

Todd[/QUOTE]

Well, we agree that a 274 is not a good cam for a mild street car. I was just giving a food for thought on the 282. Like I said, with the Hartge head and the 282, it will be more like a S38 engine, alot of top end. I guess we can quibble on the degree of torque loss at the 3-4k rpm range of the various durations/head setup.

You prefer the low end grunt, I prefer a stronger top end. I don't mind runing the car there, if its made for it. I'm not a big fan of the way the M30 lays down after 5k RPM.

In the drivers schools and autoxing, the more linear power delivery is easier to use, especially in autoxing. The 40lb-ft of torque loss at 4k is acceptable, and helps reduce wheel spin coming out of corners, this makes the car more managable. Plus the power is a little more controlable when its more linear.

Just a matter of what feel you like out of the system. I don't think emissions are an issue?

RussC

[T_C_D]

I'll agree Russ, but the lack of torque and additonal spool up time really lessen the daily driving fun. I love the part throttle torque!
Todd

[Rich in WI]

My butt dyno likes the low and mid-range grunt. It's where 99 percent of my driving will be. A little sacrifice over 5k is OK by me.

Rich

[Shawn D.]

Todd, now that I've conceded defeat on cleaning up my M30B35 while it's still together, I'm going to be taking it apart for cleaning and general refreshing. Seeing as how I intend to go with one of your systems (someday!), would you suggest removing the B35's 264 and swapping in a 260?

Sorry to semi-hijack the thread, Rich!

[Tammer in Philly]

What if the more aggressive cam was coupled to a slightly smaller turbo? I'm guessing lower peak HP/Tq, but quicker spool and good linear powerband from 3k-6.5k rpm?

-tammer <--curious ... which is always dangerous for the wallet

[QUOTE="TCD"]I'll agree Russ, but the lack of torque and additonal spool up time really lessen the daily driving fun. I love the part throttle torque!
Todd[/QUOTE]

[Jeremy]

The problem isn't the duration so much as the overlap. A schrick 282 has a lot of overlap (both exhaust valve and intake valve are open simultaneously). This aids exhaust scavenging on a naturally aspirated motor and helps the engine breathe better and make better power as the revs increase. Unfortunately, with a turbo, the turbo itself creates a small exhaust restriction. What can happen is the pressure on the exhaust side is greater that pressure on the intake side (despite the boost) and you can wind up with reversion, which is when air/fuel and exhaust move backwards through the motor instead of forwards. This leaves exhaust gasses in the cylinder and doesn't allow as much air/fuel into the cylinder as possible since there's already exhaust gasses in there. These exhaust gasses are very hot, which could lead to further reduced power and even pinging.

Granted, that's a bit of a worst case kind of scenario but that's why high overlap cams and turbos generally don't go together. A smaller turbo will create more backpressure and actually make the problem worse, not better.

Now, if you could find a high duration cam with a small amount of overlap, that'd be the thing to use. That's why stock cams are good to use, carmakers generally don't use cams with a lot of overlap due to emissions concerns.

Jeremy

PS - the preceding is all theory. Often in the forced induction world, real life doesn't exactly coincide with theory. That's why we get to argue over which cam is "better", lol.

[Edit by Jeremy on [TIME]1127486738[/TIME]]