Classic 3.0 motor build?

[kenikh]

Shaun, give me a call and I will give you a verbal download on Jeff Higgins motor. Simple to build and everything you ever wanted.

[Shaun @ Tru6]

Kenik, I'm sorry, I just saw your post. I'll give you a call tomorrow.

Thanks Ed, good to see you.

We had a very good day taking the motor down, mostly good, maybe a little bad. I'll post pics tomorrow.

Want to get advice on these pistons. I can get them for just a little more than JE's so I must consider them. Is there a specific motor I should be building with forged Mahle motorsport 3.0RSR pistons? What do they need in terms of induction? Reason I ask is that I got the motor in the 73, the mystery 69T case with Webers to run beautifully on Saturday. it's a strong little motor whatever it is, and the carbs are running like motronic...warm anyway...turn the key standing outside the car and it starts right up and idles smoothly. That means instead of considering PMOs for this build, I'd be smarter to just rejet my Webers. My question is will these 40s be up to the task for these pistons and proper cams? Also, is it as easy as sending my cylinders to EBS to be replated to match these?

Thanks so much for the help. I hope it's not too abundantly clear that I have virtually no knowledge about building motors, but I am eager to learn.

[BURN-BROS]

The Mahle's should get you about 9.7-1 with SC heads (IIRC). They are a very nice piston with good valve pockets.

[kenikh]

Buy the Mahles - those are really, really nice.

[Shaun @ Tru6]

Given the data here, these are mighty small, but I assume EBS can replate my cylinders to match?

Question: wrist pin size. How can I confirm if these will match up to my rods?

[tom1394racing]

Shaun

I used those same pistons with new matching Mahle 95mm cylinders in my 3,0 RSR clone motor.

Another RSR Clone Project - Dyno Day

Not cheap to build but runs great on both steet and track.

Let me know if you'd like more detail.

[Shaun @ Tru6]

Tom, your motor is quite an inspiration! Just wow!

After talking with Kenik (thanks!) and then a lot of back and forth with Jeff Higgins, I'm going to build a carb'd version of Jeff's motor. I still have some questions that need answers to but I should be underway in a week or two.

3.0 case
My Nikasil cylinders matched up with the 3.0 RSR pistons by EBS
My CIS heads refinished and twin-plugged by Anchor Atlantic
question: Aaron calc'd the CR at 9.7:1 above using my heads with these pistons. How can I increase CR? Jeff cautioned me about mixing these pistons with late heads and getting a low CR btw.
John Dougherty GT2-102 cams, also his sport springs on the heads
Spark from either Aaron's distributor set-up or Electromotive
Weber 40 IDAs
Early heat exchangers
M&K 2-1 muffler

What am I missing? Thoughts on specs?

[wilke3169]

This sounds like fun. Glad I subscribed. Those pistons are quite a find.

[trconway]

Shaun,
From what source will you get the twin plug distributor?
Thanks
Tom

[Shaun @ Tru6]

Tom, Burn Bros. (Aaron) up above a few posts makes them and they are arguably the best solution for twin-plugging these days.

[trconway]

Good to know. November Excellence magazine has a write-up on a gorgeous Tour de France 911 and in the article they mention Burn Bros in Fallbrook, CA as the source for the twin plug distributor. I was unable to locate a business by this name in Fallbrook. Now I know.

Good luck with your build.

Tom

[tom1394racing]

Shaun

you can have the heads fly cut to reduce the chamber volume for the stock number of 90 ml to 84ml.

This will give a CR of 10.5:1

What's Your Head Volume?

Weber 40's will be too small if you run the right cam and have the ports opened up. You need 46's.

[dtw]

Agree w/above, if you're twin plugging, then get the compression high enough to make it worth it.

Not sure why you want to ship stuff to multiple shops, I'd just send it all to EBS. They did my last set of heads, best work I've ever had. Really excellent documentation of work performed & measurements taken came with the heads, too.

[Shaun @ Tru6]

I hope my stream of consciousness, evolutionary posting isn't annoying. It's just what it is, going through the motions of building a great motor while learning about all the options and getting a lot of professional, sometimes obliquely conflicting information. I was talking with Don RE: matching the P/C (he's been great) and he won't be able to give me a firm answer on CR until he has them in hand. he noted that if CR works out to 9.8:1, I should just stay with single plug and 93 gas. So if I am on a budget, should I sacrifice some hp and stay single plug, keep heads as is and maybe a year or 2 go all out or do I go all out now. Many many options and making one selection effects the next assembly and so on. Sure, with $10K, I could just spec it out pretty fast. But I need to balance budget and assets on-hand against the final hp reward.

engine teardown pics next.

[kenikh]

OK, some comments on the CR business.

Originally Posted by dtw

Agree w/above, if you're twin plugging, then get the compression high enough to make it worth it.

What is high enough? Steve Weiner preaches that anything 9.5:1 and higher can significantly benefit from twin plugs due to the fact that you can dial in an ideal ignition curve. He feels that Porsche motors on pump gas should stick to no higher than a measured 10:1 CR with twin plugs. His assertion is that anything higher is robbing Peter to pay Paul in terms of the fact that you will have to dial back ignition timing to accomodate the higher CR.

Originally Posted by tom1394racing

you can have the heads fly cut to reduce the chamber volume for the stock number of 90 ml to 84ml.

I am perplexed as to how compression goes up from flycutting heads when you have to back the head out the same amount you machined off to get your deck height back to 1mm. That is unless you machine your piston crowns, too.

[BURN-BROS]

Originally Posted by kenikh

What is High enough? Steve Weiner preaches that anything 9.5:1 and higher can significantly benefit from twin plugs due to the fact that you can dial in an ideal ignition curve. He feels that Porsche motors on pump gas should stick to no higher than a measured 10:1 CR with twin plugs. His assertion is that anything higher is robbing Peter to pay Paul in terms of the fact that you will have to dial back ignition timing to accomodate the higher CR..

Very true.

Originally Posted by kenikh

I am perplexed as to how compression goes up from flycutting heads when you have to back the head out the same amount you machined off to get your deck height back to 1mm. That is unless you machine your piston crowns, too.

You do not back down your deck since deck has not changed.(you have not machined the cylinder as this would effect deck!)

[kenikh]

Originally Posted by BURN-BROS

You do not back down your deck since deck has not changed.(you have not machined the cylinder as this would effect deck!)

Ah - sooooooooooo...

Then as long as you don't have interference issues between the piston crown and cylinder dome, you are good to go then. Nice to know. Well that and making sure your cam chains still work without too much slack.

[Shaun @ Tru6]

Teardown pics.

Hmmmm






Most of the barrel nuts were on "wrist" tight.



My camera sucks. Should show good crosshatching. Magnet was sticky.












Need a little welding/filling here.

[Shaun @ Tru6]

few more, I'm getting ready to pull all the studs and start cleaning next week before having it decked.

[golfbuddah]

Hey Shaun I have a great tool kit you can borrow. :-)
Frank