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Aug 2003 fastrack.

3490 Views 39 Replies 9 Participants Last post by  baz
It seems I have died and gone to heaven.

Am I reading this correctly?

It seems we have a competition adjustment in our favor. The 1900/Ascona and the Manta can now leagally use the 9.0:1 pistons and the GT intake valves.

On that note do the 40mm or 42mm intake valves create more flow in an unported head?

I know in the Volvo heads I have been working with the larger intake valves actually loose flow due to loss of velocity (no matter how the rest of the head is ported or the cumbustion chambers are modified).
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There was mention about harden seats.

Here is a site for the manufacture.

I believe this is the correct brand.

TGSI Racing said:
Rally Bob... Come over to the dark side? I guess that I've always been on that side since I've always liked the Mantas a lot. It's just that they could never legally be made to run anywhere near the front. As far as handling goes, I think a properly done GT and Manta will be about equal. So the real difference will come down to the FI. With a real engine management system (electromotive) stuffed into the stock housing, the FI will probably make enough more HP to bring me completely over to "the dark side".
*****I think you will like the Manta's greater suspension tunability. It has a better camber curve, more caster available, less bump steer, a wider track, a solid-mounted rack and pinion, more suspension travel front and rear, better shock absorber geometry, etc.

I recall in the days when I crewed on my friend's 'Mini-Stock' Opel Manta...the guys running the Nascar Modified Tour cars would stare at the car's suspension, and remarked that it looks like it was built as a racecar from the factory...they liked the suspension that much. The only criticism was usually the lower a-arm/sway bar attachment on the front suspension...but rightly so, it's the worst part about the car.

TGSI Racing said:
Would any year Manta work just as well? Yea... considering all the stuff it takes to turn it into a front running ITB it really doesn't make a lot of difference.
I'd still consider running a '71 or '72 Manta. The heavy bumpers/frame reinforcements add a bunch of weight. There were no side impact beams in the doors (another 22 lbs off the car). As I mentioned, the earlier Mantas had no b-pillar (I think I inverted this statement in a previous post), but had a double-layer inner rocker panel. This adds a lot of chassis stiffness, similar to welding a rollcage tube along the inside of the rocker panel. Just my 2 cents worth.....this would be my first choice for a Manta.
The advantages Rally Bob mentions for the Manta are correct. And he is also correct that stiffer is better... chassis I mean. We achieve A LOT of that with the roll cage... just as Bob said, along the rocker pannel.

But there are some disadvantages. The front sway bar and lower A-Arm that bob mentions. Also, compared to the GT, the Manta has a higher center of gravity, greater polar moment of inertia, heavier front percentage of weight, larger frontal area and coefficient of drag.

What does all this add up to? The truth is I'm not sure. But I think the real difference is the HP gain with a FI system using an aftermarket engine management system "shoe-horned" into the stock computer box. By the way, I was asked a question earlier today about why not use a "piggy back" computer... the answer is that the rules don't allow it. Any modifications must be done inside the stock box.

So, the only way to really find out is to build a Manta and find out... so, I'm seriously looking for a suitable project car.
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TGSI, although the Manta has 54% front weight, a lot of it can be altered legally. An aluminum radiator helps a bit, a header is lighter than a cast-iron manifold, the main hoop of the rollcage can be shifted rearward, as can the driver's seat (assuming the driver has long legs!). The fuel cell can be shifted aft a touch too.
All these things ad up and can make about a 2% change in front/rear balance.

The internals of the PSC1 piggyback unit made by Split Second www.splitsec.com will fit neatly with the existing ECU inside the original box. You may want to at least look into the specs of the unit. I have used this calibrator to re-map very modified cars with large injectors and larger MAF meters using a Motec wide band A/F meter and a chassis dyno. The best thing is that it only costs $250.

Also my 2001 GCR says that the factory ECU must be unmodified. At your convienience can you get me the wording form a current source?

Yes, this was a change in 2002 and has been slightly modified for 2003. It's a very long section now and there are two or three pieces to it... I'm too tired to type it all in here tonight. But it's there.

I looked at the PSC1 and the others, and it doesn't look like it will fit inside the stock ECU box. I don't know what the "guts of their box look like, but their diagram shows it to be 1.475" thick. Also, it requries additional sensors (MAP sensor) so, you can't use it. (One of the sections of the GCR prohibits additional sensors... this was in direct response to my design which included accelerometers, and a tiny rate gyro so I could have full traction control... really, that's not just made up.:D)

I also, looked at the other models they have. The PSC3 would looks clever and would give some modest improvements. I think I might even have use this when the rules only allowed modification of the signals from the sensors. However, I don't see anything there that will turn the stock 1975 Opel dynasour ECU (slow 8 bit computations at best with a very small maping table) into a modern engine management computer with sequential fire injectors, programmable engine temperature compensation etc. and enough compute power to fill a room full of 1975 computers.

The price is attractive. And that's unfortunate because it will probably sidetrack some into thinking that's enough to win. Maybe in some regions, that's true, but in most regions, Improved Touring is one of the toughest classes to win in. I think this is another one of those cases of spend $250 to get out cheap... and then spend $2500 more if you want to win.
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The PSC1 version I use does not require a map sensor and has as many adjustable cells as any of the affordable engine management systems. The internals of the PSC is very compact. I opened up a 75 efi control unit and it looks like it will fit between the two circuit boards.

I think you are underestimating the tunability available with such a unit. I have experience in both stand alone EMS and these
"piggyback" units and can attest that the tuning for power is equal.
If suspect that you may know something their online literature and spec sheet doesn't say. All of their documentation show a MAP sensor in the system.

All their literature says is that their unit modifys the output from the mass air flow sensor according to a programmable table (to confuse things this kind of "look-up-table is also called a "MAP"... as in road map, not map sensor). While that will indeed make some improvements, it can't possibly turn a "smog special", batch fire '75 ECU into a modern engine management computer.

Everyone interested in fuel injection should go to http://www.electromotive-inc.com
Read/download their information on the TEC3 to see what a real computer can do. I think you'll see the vast difference.

That said, the PSCx is only $250. So, if one's budget can't afford to go for the win, then this unit could be second best.

I have followed products by electromotive since Don Davendorf started the company in the eary 80's. I Know the Tec 3 well. You will still need to use the MAF meter from the L-jet, and the tec 3 is MAP/RPM based. The Tec3 also has full ignition control that is not allowed in IT. So what Electromotive product would you actually use? Maybe this is allowed in IT now, I am still waiting for my 2003 GCR to arrive. No doubt this is the way to go on your GT-4 car.

What feature(s) of a fully programmable EMS do you think are an advantage besides full control of the fuel mapping on an IT car?
I guess the answer is far too long. But the most significant is sequential fire fuel injection is vastly superior to batch fire. Second, the precision with which a modern computer can control the desired pulse with of the injector will never be matched by the '75 ECU. So even if you modify only the Mass Airflow Sensor, you can never match this stuff until you replace the ECU.

The ignition rules say, "Any ignition system which utilizes the original distributor for spark timing and distribution is permited"

So, yea, it does seem a waste to not be able to use all of the powerful ignition timing stuff that's inside the Electromotive unit. So, you end up having to buy something else to do the ignition. Specifically, Haltech has a computer that will give full ignition curve using the distributor. Or you could buy the Haltec Engine Management System, but it does not give nearly as good of fuel control/sequential injector control.

That's one of the problems with "IT" rules. They don't necessarily make it prohibited to do something... they just make it more difficult and more expensive. There are many examples of IT rules that merely make it expensive. This computer rule "must fit inside the existing box" and specifically prohibiting "piggy back" boxes is one example. It can all be done within the rules... just more expensive. But indeed all classes have similar problems. It's all just the cost of winning.
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iv'e been reading this with a lot of intrest as its a form of moter sport we dont have this side of the pond

one question 4 tgsi (sorry dont know your name)
can you use the sequential injection from a later opel such as all 2.0 litre ECOTEC here have it and can be chiped to your needs?!!!

power, torque,you choose heck one company even offers a chip for towing trailers (very high torque not so much power)
In theory, and maybe in actual practice, it could be done. The "chip" that is in the computers contains a table of values (called a MAP) that determine the duration of each injector pulse based on a variety of engine sensors and conditions. So, a "chip" could be programmed that would be appropriate for an engine such as the CIH 1.9L.

The ability to use the ECOTEC computer would depend on the sensor inputs required by the computer. As long as the CIH engine matched it would be no problem. For a street driven car, you could either add new sensors, or not connect sensors as necessary. However, the governing body (Sports Car Club of America - SCCA) in their "infinite wisdom" has deemed that addition of sensors is not allowable.

I could not agree with you more on a couple of things. First that the IT rules are out of hand when they allow tons of money to be spent to make a winning car. That in itself is contrary to the class belief that is stated at the front of the IT rules. And also, yes the resolution of modern aftermarket EMS is far superior to the analog system used in early L-jetronic such as our '75 system.

Also it is possible that the Split Second piggyback sytem for a L-jet does need a map sensor (the Volvo hot wire mass sensors that I use do not, I will have to talk with the engineer) leaving us both SOL on this front.
Yea... but it is also the competitors themselves... like me, they figure out a way to get more performance within the rules. Now days, for McPherson strut cars, full "coil over", full adjustable suspension is the accepted norm. The rules were intended to limit that... but folks figured out a way to have in effect full "coil-overs" and still stay within the rules. It even got to tripple adjustable Penske shocks at all four courners becoming very common... at $1000 each. (The rule has been changed to allow only double adjustable shocks... only $400 - $500 each for the good stuff.

But it is like all racing. Folks thinkin'-n -dreamin'-n-schemin' ways to go faster than the next guy. I guess that's what winning is all about.
Yes sir that's how it tends to evolve. If the rules are written properly they would cap the modifications possible.

If one wants to spend all that money they should build a Production or GT car so we do not have to sell the farm to be competative. Like that argument has never been made, right?
You can't be competitive in a Production Opel (Manta or GT)... or any other brand of car without at least $50K in the car.

And a "bare rolling chassis" (tube frame) for a GT starts at $25K. Engine - 10K bare minimum and probably closer to 20K. Transmission, seat, radiator, body work, plumbing, seat, instruments, fuel cell... and on and on... so you can figure on around $75K or more.

So, relatively speaking, "IT" is still an "inexpensive" class. You can build a front running car for a little less than the price of a new, nicely equipped, mid size Ford, Chevy, or Chrysler car.
WOW! 50 to 75K

i wish i had know before i got involved

ON the Manta FI I think you need to have some idea of the air flow of the 75 Manta FI setup

so before you even go spending big money on ECU's is the cost worth the results

seems you are always pushing up against the weak link in the chain

the only real info i have was an article in the Blitz some years ago about a guy in CA that dynoed an 75 Manta IT race car.

and me running my street GT at the drag strip

ran 19.2 in the 1/4 mile went to 1.5 head and FI and it ran 18.5

many many passes

as for sequential or batch fire check this out


when i put the 75 FI ECU on an "O" scope the amplitude changed and not the duration
still scratching my head on that one

and not a clean square wave like you would think crappy sawtooth wave but hey maybe that's all that's needed

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Well, regardless of the FI issue, I'm just happy I can now legally run the larger intake valves and the flat-top pistons. It would suck running my Ascona with *75 hp* against the local Volvos with 148 hp (dynoed numbers!). Now at least I know I can get 110-115 hp with legal mods and a Weber.

eco tec

the eco tec runs a temp sensor a knock sensor fuel rail pressure sensor and the timing is through the distributor i,ll have a look round 4 a wiring harnes diagram and email it 2 you
(dont quote me on this yet)
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