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EFI for 3.2SS??

I am well underway with collecting the parts for my 3.2SS.

While hunting out for some 46mm carbs I came across some info about EFI, and in particular the Bitz system. I always thought that EFI would be way too expensive but this system seems like reasonable dollars, not that much different to carbs from what I can work out.

Can anyone help me out and guide me as to whether I should consider this option or just stick with the dream that I can find find some cheap 46mm PMO's??

If it helps I am using GE60 cams, 10.5:1 JE pistons, rebored and plated 3.2 cylinders, twin plug, SSI's and dual out dansk. Car will be street with the occasional track day so I can stretch the legs and retain my licence at the same time...

Thanks.
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Old 08-14-2010, 04:47 AM
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I have the Bitz system on my SC. Great upgrade and easy to tune. Lots of info on Tony Bitz's forums:

bitzracing : BITZ Racing

The system was built on a 911SC platform.

The only thing I would recommend is the wideband O2 sensor option and a dash mounted AF/R gauge.

...but, carbs are fun too. I bet you'd get more of a HP gain, better fuel economy and cheaper system with the EFI option.

I dyno'd at 215 chp (up from stock, 188) with my 1980 euro spec SC.
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Last edited by flat6pilot; 08-14-2010 at 10:19 PM..
Old 08-14-2010, 10:16 PM
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Thanks Kyle,

I'll have a look at this. Nice car by the way. My 1st SC had fully polished wheels and I loved them.
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Old 08-15-2010, 03:29 AM
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One thing to consider with the Bitz style EFI system is the effect of the common plenum/single throttle plate on throttle response.

Throttle response is much better with individual throttle bodies like you have with carbs, MFI or EFI systems with individual throttle bodies. These type of systems give a great "kick in the pants" feel when you stomp on the throttle.

The common plenum/single throttle plate will dampen the throttle response.
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Old 08-15-2010, 06:48 AM
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Quote:
Originally Posted by tom1394racing View Post
One thing to consider with the Bitz style EFI system is the effect of the common plenum/single throttle plate on throttle response.

Throttle response is much better with individual throttle bodies like you have with carbs, MFI or EFI systems with individual throttle bodies. These type of systems give a great "kick in the pants" feel when you stomp on the throttle.

The common plenum/single throttle plate will dampen the throttle response.
Thanks Tom. When I saw the info I wondered why I hadn't heard alot more about EFI conversions, perhaps factors like this play a part.

There seems to be some 'happy customers' and I'm sure it has it's benefits, whether it's right for me I am not sure. The throttle response issue is a significant factor.
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Old 08-15-2010, 04:00 PM
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I stayed with my tbitz efi when i rebuilt my 3 to a 3.2SS and couldnt be happier. Took car to europe last year and it performed all i asked of it... hung with new audis and bimmers on the bahn

Targa to Sicily

Great flexibility, easy tuning, and hey, the price cant be beat.

I tuned the car to use the stock common plenum, and milder cam but with SSI, so i lost some hp this way, but the torque and throttle response are great

3.2SS with MS EFI dyno results
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Old 08-15-2010, 06:33 PM
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Thanks juice. There's a fair of reading here but it looks like great info, much appreciated.

I'll go through all these links and youtube vids.

Lucky my engine builder is booked up until next year - it might take me that long to settle on a final config!
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Old 08-15-2010, 06:45 PM
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This sounds like a fun motor and this type of build has been proven. I would highly suggest EFI using ITBs. The DC60 cam will want to run up to at least 7500 (and will still pull hard). At this engine speed I personally do not think that a common plenum setup (3.0 or 3.2) will support the airflow required. Adapting a 3.6 manifold is another story.

My first question would be... What do you want to do with the car? The DC60 cam is great but is designed for high rpm applications such as DE or track. If you are more likely to spend time on the street or AX I would suggest less cam to build in the torque down low. Likewise, the DC60 cam would benefit from shorter gears to match the high-rpm nature. Your stock SC gears may feel tall and make the car feel somewhat lethargic. Keep in mind these are subjective thoughts. Overall, the new engine will greatly outperform stock. It is just the notion that you want to modify the drivetrain as a complete system where every part works in synergy.

I might recommend the 40 cam similar to what Justin built. I have the same cam in my ST replica. I really like it. I had mine ground with the 108 lobe center. This helps the EFI get a nice smooth vacuum signal through reduced reversion pulses. Overall, this would not be a problem with a common plenum however it is an issue with ITBs.

I am sold on EFI and like the fact that you can tune the engine to run well (optimum) everywhere in the power curve. This can sometimes be difficult to do with carbs. btw, if you search you might find that you can buy TWM 3003 ITBs for possibly less than you would spend for 46mm webers/PMOs.

I do like the tbitz kit for stock applications. Otherwise, buy a built Megasquirt system ($400) and assemble your own EFI around it. Get the MSII chip and run the MSII-Extra code for increased table resolution and newly coded ITB mode. This will greatly enhance your drivability.
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Old 08-18-2010, 07:58 AM
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Sorry to be a wet cloth here but even a single TB EFI responds better than the carb set up (if your tune map is right) Theres absolutely no reason not to run EFI (unless your doing a restoration and want carbs for authenticity) the EFI out performs the carbs on every single level and todays prices are cheaper than PMOs
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Old 08-18-2010, 11:37 AM
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EFI is great but I don't think you're going to get the same bang-for-buck as carbs. EFI will have to have ITB to work as well as 46 Webers or PMO and the GE60 cams are perfect for carbs. The notion that the cams are peaky or have no low end is unfounded. Sure, they come on the pipe very noticeably at around 5500 rpm but below that they are very streetable. For everyday running around town you won't know it isn't stock but when you mash the loud pedal you'll know their there.

There have been two sets of 46's in the last three weeks that sold for $1500 complete with manifolds and air cleaners. Good luck finding a comparable EFI set-up for that price that will perform with the carbs.

Why not build this motor yourself? From the sound of your questions it seems like you have the knowledge to pull it off.

Lindy
Old 08-18-2010, 01:15 PM
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There is definitely 2 sides to the argument here. I can see the technological advantage of EFI but part of me can't move away from carbs - whether it's right or wrong I love the idea of a older 911 with big cams and carby's.

I'm not going to race it, I just want one in the garage When I bought the DC60's I thought alot about the streetability. Like carbs v EFI there are 2 schools of thought but in the end I had enough feedback to give the big cams a go.

My skill levels are fairly basic and I am learning as I go. I'm just getting my head around everything and the thought of EFI is a bit daunting. If I end up with carbs then I can always move on to EFI later. - maybe not the most economical way to go but it's always an option. I know that the resale on 46mm carbs is pretty good.

I am negotiating with a fellow Pelicanite on a set of PMO's. If that works out then case closed, but if not I'll research some more into EFI. Cost will probably be the biggest voice in my head.

I appreciate all the comments here - these forums are my #1 source of information.

Lindy - any dyno sheets on your build?
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Old 08-18-2010, 04:22 PM
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Quote:
Originally Posted by esotoracing View Post
Sorry to be a wet cloth here but even a single TB EFI responds better than the carb set up (if your tune map is right) Theres absolutely no reason not to run EFI (unless your doing a restoration and want carbs for authenticity) the EFI out performs the carbs on every single level and todays prices are cheaper than PMOs
+1 add may I add: 36 mpg on a 3.2l isn't bad.
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Old 08-18-2010, 05:31 PM
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Can someone point me to a 'kit' that will suit a 3.2SS? For me to consider EFI I much prefer the idea of a complete setup.

I would feel much more comfortable with a tried and tested setup that I can just install and tune on the laptop, and where tech support is available.
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Old 08-18-2010, 05:50 PM
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MoTec, about $10,000. You'll never see 36 mpg from the motor you're building no matter what induction system you choose. If it's used like mine then the 18 mpg it gets does not bother me. Most things fast don't get real good fuel economy. It takes a quantified amount a fuel to make a quantified amount of HP. Some systems do it fractionally better than others.

Lindy

Last edited by lindy 911; 08-19-2010 at 06:35 AM..
Old 08-19-2010, 06:31 AM
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Quote:
Originally Posted by D911SC View Post

Lindy - any dyno sheets on your build?
++1, LOL

As for 'kits', it doesn't get any easier (and i dont think there any other 'kit' options out there for specifically for the 911 anyway) than the TBitz kit my friend. While Tony (the guy who designed and sells the kit) doesn't give telephone advice anymore like he used too, this is irrelevant, as the guys on the online Yahoo Tbitz group bitzracing : BITZ Racing (some of them Pelicans) will be more than happy to guide you through the tuning basics and problem solving. Like Jamie said, the flexiblity is incredible, and starting with the Tbitz kit allows u to learn the basics, and then u can build on your knowlege base using all of the vast array of tuning aids http://www.diyautotune.com/tech_articles/street_tuning_your_megasquirt_ems.htm , http://www.megamanual.com/v22manual/mtune.htm for MS EFI as u go. Like yourself, i started as a novice, and while i still am, learning EFI tuning via the MS is both fun and straightforward once u get into it. I decided to go with MS EFI vs carbs due to the fact that my ultimate goal is to build and tune my own turbo motor and I need to know EFI tuning skillz for this.
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Last edited by juicersr; 08-19-2010 at 06:39 AM..
Old 08-19-2010, 06:36 AM
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I'm curious why asking if dyno runs have been done is reason for "LOL". There are dyno sheets from Gerts 3.0 posted that show 330 HP from a very similar build to mine. He used DC62 cams and PMO carbs naturally aspirated. You think the Tbitz kit will do that? I think not.

Lindy
Old 08-19-2010, 06:45 AM
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Whatever you build, don't expect to just bolt thing together and drive. Wether you go carbs or EFI you will need to do lots of tuning to make it run well. You need data to tune. If you go with the EFI you are doing lots of runs looking at maps and changing tuning with a computer. If you go with carbs (like I did on a race car application) you have to monitor your A/F ratio throughout the power band. To do this on either application you will want to be able to push the throttle to the floor and hold it there to red line. Track, dyno, street? It takes time and knowledge to get it right. No doubt you can likely build it but the trick is to get it to run like you want it to. Plan to spend time and potentially money to get it right. I really like my 3.2SS, they are great fun.
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Old 08-19-2010, 07:08 AM
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Quote:
Originally Posted by lindy 911 View Post
I'm curious why asking if dyno runs have been done is reason for "LOL". There are dyno sheets from Gerts 3.0 posted that show 330 HP from a very similar build to mine. He used DC62 cams and PMO carbs naturally aspirated. You think the Tbitz kit will do that? I think not.

Lindy
Hey Lindy, was laughing because u are probably tired of me asking for a dyno run on your build. Each build characterisic is slightly different, and a dyno just helps to cut through all the BS that gets tossed around on the forum with some cold, hard numbers, that's all. Hey, i put my money where my mouth is after my build last year, BTW 3.2SS with MS EFI dyno results Ok, i will officially shut up now about asking for a dyno run on your motor. Hope u r enjoying the hell out of it!

I agree, in terms of ease of setting things up for big HP, sending PMO or performance oriented your motor specs and having an out-of-the-box carb ready to go cant be beat. However, tweaking ITB's with MS EFI is great way to go too.
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Old 08-19-2010, 07:59 AM
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Understood; I didn't make the connection, sorry 'bout that. I will post the dyno numbers this fall. I'm in the process of finishing off the other parts of the build including the suspension and chassis mods as well as the interior. I have a pile of parts that weigh about 470 pounds on the garage floor and I'm not through. The motor has been broken in now and I can only say that it is very fast. Runs like stock until 5,000 or so then it just rips to 8,000; what a blast!

Lindy
Old 08-19-2010, 08:27 AM
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im about to embark on an megasquirt install on my SC. im building the injecton my self and plan to run both fuel (with live wideband tuning) and spark off the ecu. not sure yet how i will use to get cranck positon but once i get that figured out ill start pulling my motor out and geting into stripping it.

biggest thing w/ megasquirt is if u dont have the will power to make it work no mater what happens its probably never going to work properly for you. where with carbs or other efi systems its fairly easy to get someone to do the setup for u if need be. i dont seem to see many shops willing to work with megasquirt due to there being too many things to possibly be an issue.
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Old 08-19-2010, 10:45 PM
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