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Quote:
I like them both but for different reasons.
+1
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Old 07-16-2007, 06:03 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #41 (permalink)
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Quote:
Originally posted by 125shifter
I'm not buying the 20mpg with any fuel system. Maybe downhill with a tailwind. I'm still getting about 10 mpg with EFI, although I've never driven the car without getting into the boost.
I have no numbers post EFI. But my CIS Car ran 9-10 MPG in Town and 23-25 MPG Pure HWY at 65 MPH. My suggestion here among others is most of you probably don't drive the car 800 miles a day on the highway to gert accurate Road numbers. My experience was every couple MPH above 65MPH started nibbling pretty heavy on the MPG. One of the problems with a 930 is who can cruise it at 65 MPH for 400 miles or so. I used to do this type of driving to get to a remote work site. I had to avoid attracting the State Police and it was in the 55 MPH days. The DEVIL beckons, it is hard not to want to BLAZE up an on ramp, or squirt past a car. My car at that time was a EURO 930 with all federalization stripped off and in a good state of tune. I experienced a car that Guzzled Gas in town and sipped it on the road. My .02.

Les
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Last edited by les_garten; 07-17-2007 at 06:29 AM..
Old 07-17-2007, 06:00 AM
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Joel, you might want to try driving your car for a couple months before launching into something as potentially time consuming as EFI.

I find that the more I drive the car, the less it really needs. And then I can focus on what mods I really want now versus later. No reason to do work twice.

The 944 Turbo is a well EFI'd car, and it is a dog below about 3,500 rpms or so. Guess why? Because EFI does not help much in a small, mild compression engine until the turbo kicks in.

The only way you are going to increase your low end pick up is with less weight or a closer ratio gearbox to keep you on the boost at highway speeds.

EFI will make your engine run cleaner and optimize throttle response, but it won't do a hell of a lot until you are actually on the boost except make sure your timing is advanced the way you want it.

Last edited by DDDD; 07-17-2007 at 07:40 AM..
Old 07-17-2007, 07:22 AM
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Quote:
Originally posted by DDDD
Joel, you might want to try driving your car for a couple months before launching into something as potentially time consuming as EFI.

I find that the more I drive the car, the less it really needs. And then I can focus on what mods I really want now versus later. No reason to do work twice.

The 944 Turbo is a well EFI'd car, and it is a dog below about 3,500 rpms or so. Guess why? Because EFI does not help much in a small, mild compression engine until the turbo kicks in.

The only way you are going to increase your low end pick up is with less weight or a closer ratio gearbox to keep you on the boost at highway speeds.

EFI will make your engine run cleaner and optimize throttle response, but it won't do a hell of a lot until you are actually on the boost except make sure your timing is advanced the way you want it.
Oh absolutely!

This idea got shot down almost right away after seeing the expense to gain ratio.

I think the route I will take is eventually buying a tunable WUR and the tools I need to tune my CIS, and be happy with a car that is plenty fast as is. As someone mentioned, after dumping loads of money in doing the conversion, he would have been better off just buying a newer Porsche that is already there.
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Old 07-17-2007, 07:52 AM
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Quote:
Originally posted by DDDD


EFI will make your engine run cleaner and optimize throttle response, but it won't do a hell of a lot until you are actually on the boost except make sure your timing is advanced the way you want it.

Sorry but, that's not accurate. A good aftermarket engine management can still provide substantial improvements (not necessarily peak power wise) even off boost. With older turbocharged cars from the '80s and '70s that have older injection setups and turbo systems, usually stock stuff is much more focused on the powerband on boost, and usually not so much so on off the off boost powerband. Even smaller displacement cars like 944's can benefit from a good modern EFI. Rather then defaulting to the typical "emotional" terms such as it's magic, or it's a PITA, etc etc, lets talk some actual facts. Compared to old factory EFI systems, CIS, etc etc, modern EFI systems generally have faster processors, larger number of tuning load sites, ability to fine tune a larger number of parameters, some systems give you the ability to use advanced ignition or injection systems (coil on plug, sequential injection, etc). How do these things make any improvement? Well, with a larger number of available load sites for tuning, you can more finely tune at smaller rpm intervals over a broader rpm range. How does that help? Well, you can actually focus on tuning below 2000rpm and achieve much better torque and response below 2000rpm, which can have a substantial improvement on off boost performance, lugging the motor through traffic, etc. Don't believe me, go ride in a well setup EFI'd older car (preferrably something nice like a Motec setup) and you'll see what I mean. In addition to that, there are plenty of improvements to be made in "tip in"/partial throttle response, maximizing torque throughout the rpm band, etc. Anyone that doesn't think so either has never been able to successfully setup an aftermarket EFI, or has never experienced a properly setup one. TUNING is everything with any EFI setup, and unfortunately that is the easiest part to screw up as it truly is some sort of art form.

For the do-it-yourself'ers out there, there is no real reason a typical EFI setup should have to cost more than $5-7k for the EFI components + tuning. I realize with 930's there are other things such as injector blocks and intake manifolds to consider, but I'm just talking about the EFI setup itself and not turbo/cam/head/etc upgrades. Much over $10-20k as some 930 setups are advertised and well over 50% of the cost can usually be attributed to labor rates IMO. There are a few companies out there with plug and play setups like DTA, Tec3, etc for less than $5k so it can be done relatively inexpensively. Regardless of anything else, just don't skimp on the tuning. There's no real point doing an aftermarket EFI if you don't have the tuning to actually take advantage of it. For sub 500whp levels, the CIS has been made to work just fine for quite a few years, so technically, yes, there are better areas to spend the money than an EFI setup. For anyone considering over 500whp though, I wouldn't exactly say starting with an EFI setup is necessarily a "bad" route per se. True, there are more initially effective ways to spend the money, but you could also think of it as starting out with better components in the first place. This is the same as the age old EFI vs. carbs argument.
Old 07-17-2007, 12:34 PM
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Quote:
Originally posted by DDDD

[snip]

The 944 Turbo is a well EFI'd car, and it is a dog below about 3,500 rpms or so. Guess why? Because EFI does not help much in a small, mild compression engine until the turbo kicks in.

[snip]
Ummm..., not really.

You can set up your tables to provide more ignition advance, a proper AFR for the kPa/RPM, and then a bit of accel fuel, and you can wake that motor up. In addition, it will spool the turbo a bit quicker too.
Old 07-17-2007, 06:24 PM
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Sense I am playing Devil's advocate I'll add this:

Nither CIS or EFI have anything to do with the ignition system.

They are fuel delivery systems. If we want to include ignition then we should use the term "engine management system". You can run an ignition management system with CIS. It has been done by a few folks here on Pelican.

There are stand alone EFI systems on the market such as MegaSquirt that are not too terribly expensive. You still have the set up and tuning to contend with. These type systems can add ignition control later which may be a nice option for some folks considering EFI or engine management.

Speaking of ignition control, any good backyard mechanic old enough to remember the horse power crisis of the mid 70's knows how to modify the advance curve on a distributor. If you want to compare engine management systems to CIS then distributor modification needs to be mensioned as well.

All that being said, for a fraction of the time needed to set up an engine management system you can tune your CIS and modify the curve on your dizzy. The results are astounding when compared to stock. Both of those systems have to be addressed if you are to compare CIS to electronic engine management.
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Old 07-18-2007, 06:55 AM
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Quote:
Originally posted by DonE
Ummm..., not really.

You can set up your tables to provide more ignition advance, a proper AFR for the kPa/RPM, and then a bit of accel fuel, and you can wake that motor up. In addition, it will spool the turbo a bit quicker too.
Ummm..., yeah, really, the 944 turbo is a dog below turbo boost.

And you can set ignition advance and a proper AFR and add a bit of fuel using a fuel head for CIS and an aftermarket ignition. Not as well as EFI when tuned exactly right, obviously.

So do you think that you can EFI a 944 turbo to the point that it will leave a stoplight in top gear, like, say, any muscle car?

Do you think that a dog bottom end in all these 3.3 litres or less cars is going to be twice as good with a well sorted EFI than a well sorted CIS? Not quite.

A small and mild compression engine is a small and mild compression engine no matter how you tune it and you are kidding yourself if you think otherwise.

Last edited by DDDD; 07-18-2007 at 07:31 AM..
Old 07-18-2007, 07:26 AM
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SNIP

For sub 500whp levels, the CIS has been made to work just fine for quite a few years, so technically, yes, there are better areas to spend the money than an EFI setup.

SNIP


Porschefile, thanks for agreeing with me...
Old 07-18-2007, 07:37 AM
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Wo ist die Rennstrecke?
 
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Quote:
Originally posted by DDDD
Ummm..., yeah, really, the 944 turbo is a dog below turbo boost.

And you can set ignition advance and a proper AFR and add a bit of fuel using a fuel head for CIS and an aftermarket ignition. Not as well as EFI when tuned exactly right, obviously.

So do you think that you can EFI a 944 turbo to the point that it will leave a stoplight in top gear, like, say, any muscle car?

Do you think that a dog bottom end in all these 3.3 litres or less cars is going to be twice as good with a well sorted EFI than a well sorted CIS? Not quite.

A small and mild compression engine is a small and mild compression engine no matter how you tune it and you are kidding yourself if you think otherwise.
Sorry to upset you.

I never compared a 944 turbo to a "muscle car". Not sure anyone would....

By the look of your signature, you have ample tuning experience too....

Last edited by DonE; 07-18-2007 at 09:17 AM..
Old 07-18-2007, 08:34 AM
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Quote:
Originally posted by DonE
Sorry to upset you.

I never compared a 944 turbo to a "muscle car". Not sure anyone would....

By the look of your signature, you have ample tuning experience too....
Don't worry then, because you haven't upset me.

If you read carefully, you will see that I never suggested that you ever attempted to compare the 944 to a muscle car, but quite simply that no amount of EFI will turn a stock 944 bottom end into anything other than a stock 944 bottom end.

For the amount of money Joel could spend on an EFI, he is half way to affording a engine rebuild with higher compression or for that matter just redoing his tranny gearing and saving some weight and so on.

Last edited by DDDD; 07-18-2007 at 09:49 AM..
Old 07-18-2007, 09:42 AM
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I think we are all in agreement.

EFI is a great modification if you have access to the money and tuning required and have some motivation to exceed 450hp.

Otherwise, it is not likely to be worth all the cost and complications when a properly tuned CIS system works well and is MUCH cheaper.

If I had it all to do over again I would have stayed with CIS. However, now that I have EFI I really enjoy it.
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Old 07-18-2007, 11:07 AM
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With 500+ HP to the ground you had no chioce but to go EFI. You're in a different league now brother.

Kirk - on another note the weather forcast for Friday is deteriorating. Right now there is a 50% chance of rain. I'll keep an eye on it today but it doesn't look good. I'll e-mail you for options next week.

In the meantime there is a race scheduled this weekend between a CIS 911 Turbo and a 2008 ZO6. Roll off at 30mph and go 'till someone gives up. Ought to be interesting ...........
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Old 07-18-2007, 11:48 AM
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Quote:
Originally posted by DDDD

[sinp]

For the amount of money Joel could spend on an EFI, he is half way to affording a engine rebuild with higher compression or for that matter just redoing his tranny gearing and saving some weight and so on.
Completely agree.
Old 07-18-2007, 12:18 PM
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Quote:
Originally posted by RarlyL8
With 500+ HP to the ground you had no chioce but to go EFI. You're in a different league now brother.

Kirk - on another note the weather forcast for Friday is deteriorating. Right now there is a 50% chance of rain. I'll keep an eye on it today but it doesn't look good. I'll e-mail you for options next week.

In the meantime there is a race scheduled this weekend between a CIS 911 Turbo and a 2008 ZO6. Roll off at 30mph and go 'till someone gives up. Ought to be interesting ...........
YOU MUST BRING US VIDEO OF THIS EVENT!!!!
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Old 07-18-2007, 01:01 PM
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Rarly, I am not a huge proponent of EFI when all the factors are considered, namely cost, however CIS is very limited, antiquated and difficult to tune.
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Old 07-18-2007, 02:22 PM
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Quote:
Originally posted by RarlyL8
Sense I am playing Devil's advocate I'll add this:

Nither CIS or EFI have anything to do with the ignition system.

They are fuel delivery systems. If we want to include ignition then we should use the term "engine management system". You can run an ignition management system with CIS. It has been done by a few folks here on Pelican.
I think the ignition improvements with an ECU are even more important than the fuel improvements. Especially when off boost. When I took the EFI101 course, Ben Strader showed us the power change with the fuel mixture off a bit, it was a small change. Then he showed us the power change with the ignition off a bit, it was significantly bigger difference. Since the ignition is tuned for each load and rpm cell rather than just RPM, this can be a significant improvement.

So you'd be giving up one of the big advantages by using an EFI system without ignition control.
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Old 07-18-2007, 03:03 PM
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It's tough to argue this point with someone who has not tuned an after-market ECU (EFI) and experienced the results.

Disclaimer: I am not trying to slam anyone.
Old 07-18-2007, 04:04 PM
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You're absolutely right Don. It is equally difficult to argue the point with someone who has never tuned CIS.

You've done both, and done both very well I might add.
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Old 07-18-2007, 05:52 PM
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Race Results: CIS 911 Turbo vs '08 Z06

Got some results for you.
The run was impromptu on Friday night instead of Saturday as planned, I did not attend but got the low-down.

First run - roll off with speed choice given to the Z06. The Corvette was in 1st gear, 911 Turbo in 2nd gear @2600rpm.
Corvette spun the tires at launch giving the Porsche a 2 car lead which was maintained to 142mph. Corvette lifted.
WIN - Porsche Turbo

Second run - same roll off with speed choice given to the Z06. Corvette in 1st gear, 911 Turbo in 2nd @ 2600rpm. This time the Porsche spun the tires and gave up ~2 car lengths which was again maintained to 140mph. Corvette lifted.
WIN - Z06

Apparently these cars are very evenly matched!

Kirk - this week is a wash but there is a fun run on Saturday to a car show in Ardmore. I plan to attend.
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RarlyL8 Motorsports / M&K Exhaust - 911/930 Exhaust Systems, Turbos, TiAL, CIS Mods/Rebuilds
'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
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Old 07-23-2007, 08:32 AM
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