Megasquirt/Bitz cam and other questions
 

Just finishing up by build plan now. Have ~$2000 in parts on the way now from Pelican and anxiously looking for a decent machine shop in Sydney...

I send Tony@Bitz some e-mail questions earlier today and he hasn't had a chance to respond (its still middle of the night where he is) but I thought I'd post the questions here so that they might help others too...I've also added some other questions since sending my e-mail. This is on a 3.0 82 US-head complete blueprint/rebuild.

1. What cams have you heard/seen perform well with this kit when tuning for low/mid-range torque? I saw your site with the dyno run (awesome to see empirical results posted) and noticed all of the project cars in the gallery section that listed their cams were CIS. Has anyone posted dyno results with other cams running megasquirted NA 930's?


2. What method are you using to estimate intake airflow? Speed-density? Don't you need a vacuum guage on the intake for this? I don't see either a MAF or MAP hardware in your kit list.

3. What are the make/model/flow at 80% duty specs for your injectors?

4. Does your "Main wiring harness (from MegaSquirt to engine bay)" on your inventory list mean the same as the Megasquirt relay board as sold by DIYautotune.com? I noticed there wasn't any mention of the relays on your manual or site, whereas they are commonly referred to and installed in discussions on the megasquirt forum. http://www.diyautotune.com/products/msrelay.htm

4a. If not, how long is the wiring harness?

5. Is the O2 sensor you include a "wideband" unit providing a linear voltage curve related to O2 readings or the standard "rich-or-lean" sensor?

6. Do you include a throttle position sensor? I don't see it on your list and I don't know how to go about installing a Megasquirt with acceleration enrichment without it.

7. Noticed several of the cars in the gallery installed the "pop-off-valves" seen on most late 930's. Some didn't. Has anyone had their valve pop after installing the Megasquirt?

8. I'm assuming Tony ships the megasquirt with a baseline map installed. Has this been extensively tuned? Have others modified theirs significantly? Would they be willing to share their tables?

9. Did anyone check the taper on their intake tubes? Did you attempt to "tune" them to create resonance waves within any certain RPM ranges?

Thanks all!

Update:
Tony came back first thing his morning with good answers for the first few questions (I didn't send him #s 6+, I thought of those later)

Thanks Tony for the fast and direct response. As I said in the e-mail, your info is always much appreciated and thanks for the thought and work you put into this forum.

"Tony,
Thanks for the fast response. I also posted these questions and more to the
pelican engine building forum. Do you mind if I post your response there for
others?

I also ask about the ve tables (how much tuning did you do from the
'standard' maps) and some other ?s.

Thanks again for your help, still figuring out what to do with my new baby!

John
--------------------------
Sent from my BlackBerry Wireless Handheld


-----Original Message-----
From: bitzracing <tony@bitzracing.com>
To: Landry, John J <john.j.landry@citigroup.com>
Sent: Mon May 02 22:50:48 2005
Subject: Re: Megasquirt setup questions

John,

Thanks for your interest. Here are answers to your questions:

1- There is one fellow (Noah on Pelican) that is running the 964 cams. I
also know another person who did his own 911 conversion with MegaSquirt with
some fairly hot cams. I can recall which ones he used.

2-MegaSquirt is a speed density system and the MAP sensor is within the
MegaSquirt unit. You need to run a vacuum hose from the engine bay to the
ECU.
3-I use 30lbs/hr injectors which are good for 280Hp at 85% duty cycle.
4-The relay board is different and not needed for the 911 conversion. All
you need is the wire harness I supply. It is 15feet long, specifically made
for the 911 kit.
5-O2 is narrow band
6-No TPS is used. If you read the installation guide I have an appendix
which talks about how the TPS is emulated via changes in MAP pressure. It
works very well.

Cheers,

Tony
BITZ Racing"

Noah,
Thanks, I thought I had read all the megasquirt-related posts. That was helpful.

Any other dyno curves out there for alternative cams on 3.0 CIS p/c's and EFI?

thanks
all

noah is right about the questions being answered, but in short:

964 cams are the safe bet

993SS cams are a bit hotter and might work

"camgrinder" on this board knows his stuff (you will find him in your search of old discussions) and I would contact him if I was more or less ready to buy for recommendations and pricing.

Thanks guys. It's dd74's question on page 2 that is what I am asking (amongst others.) His wasn't ever answered in that thread. The question is how well will the 993SS cams run on 3.0 CIS p/c's? More specifically, how WELL will it run with 3.0 p/c's woth ITB megasquirt II running speed-density tables?

I'm interested in 1. knowing if the valves will clear (yes, I'll measure but I'd like to know from the Masters before I order and put it all together)

2. What the torque curve looks like
3. If anyone has the VE and other config tables to run MS with this cam?


By the way, wouldn't Dr. Camshaft's site be great with the addition of some dyno sheets with engine config information. Sorry to keep hammering on this point. Does anyone know of a collection of dyno curves with engine info? If not, I could volunteer to host one...

thanks for all the help.
John

The 964 cam is the safe choice as Andy said. They will clear the pistons and the factory 3.0 pistons have adequate compression.
The Cup cams should have 9.5-1 or higher compression and will have clearance problems with 3.0 pistons. You can machine the pistons for extra clearance, but you will lose compression ratio.

I would love to post dyno info on my website. If anyone has dyno sheets with my camshafts send them to me.

you can search on this board for dyno charts and find a bunch.

the problem with your question is I don't know anyone on the board who has tried 993SS cams in a 3.0 with stock pistons (which as John said have to be modified, I did not realize this), let alone with megasquirt ITBs.

If you're going to run ITBs and megasquirt get yourself some 10.5:1 JEs, have the machine work done to add a second plug hole (pretty inexpensive) and megasquirt will handle the second set of plugs with cheap equipment. Then you can use something like a GE60 since you have ITBs. OR if you don't want to twin plug get 9.5:1 JEs and still run a GE60ish cam.

But that's just my opinion. If I'm going to run ITBs I'm going to take advantage of them with an appropriate cam. If I'm not, I'd run a 964 cam and be happy with it. The megasquirt doesn't buy much in terms of cam choice on a CIS motor IMHO, when you're still using a shared plenum. BA talks about the CIS flapper being affected by hot cams but the 3.2 has basically the same cam tolerance (keeping driveability) with no flapper but still a shared plenum.

Hi Andy,
Well, an update...It appears I have 9.3CR pistons in there now, and my cylinders are in good shape.

I should clarify my intake plans...I'm planning on utilizing the bases of my CIS runners but fabricating up a better intake/plenum. New ITBs would be cool, but mucho expensive.

In an exchange with John D he said he thought GE20/DC20's were OK with CIS pistons, though I wasn't clear 100% on that. I don't want to go to twin-plug just yet. I was planning on just using the stock distributor with an MSD coil and ignition for the time being, until the MSII units become available/shaken out later this year.

Anyone confirm the clearance and characteristics of a GE20/DC/20 on 3.0 CIS pistons?

thanks

What about this EFI: http://www.sakuramotorsports.com/

Re: Megasquirt/Bitz cam and other questions
 

There are no naturally aspirated 930 cars. 930 is a Turbo. Period. SC is SC and Carrera is Carrera. 930 is internal PAG designation for 911 Turbo, first generation.

See above... 930 doesn't need pop-off valves. It's only K-Jet equipped SC's that suffer backfire that need pop-off valves. 930 has turbocharged engine and never had problems with this.

Sorry, santa...all those parts I've been pulling off my case numbered "930" must have me hypnotized!

You do hit on my question though...I also thought the backfire was a symptom of the k-jets, yet I also see those pop-off valves on non-k-jet cars so was wondering why.

930 popping exhaust on deccel is not to be mixed with full-on backfire explosions that hamper K-Jet equipped SC's.

Deccel popping is just some unburnt fuel, blown airbox is intake reversion. Turbo has very long hoses (airbox - flapper - pipe . turbo - pipe - intercooler - plenum - heads) so this was never really an issue on 930's.

SC's have much shorter air-path that will sometimes make airbox go boom.