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Discussion Starter #1
Hey all....

Well I started about a year ago with the grand idea of swapping a Mazda 13b rotary into my 1970 GT, but having gone through some financial troubles, and now just troubles with trying to figure out everything with swapping the rotary in, I'm planning on going back to the stock 1.9L that cam with the car... with a few upgrades on it.

So here I go with probably a load of questions, any help would be much appreciated, and sorry if I start rambling, this is all a bit spur of the moment....


Ok, first a few things:

1. how does the 1.9 do with boost on it?
2. How strong is the bottom end, and how much room for improvement is there?
3. What's the stock compression ratio?
4. What kind of options are there for fuel injection? short of designing your own system with say a Haltech and a custom designed intake.


Ok, so with my little epiphiny here, what I'm thinking is comverting to fuel injection (I like the idea of having good cold weather starting charistics, living in Wa) and running a turbo setup with prolly somewhere in the 9-15psi boost range, depending one what kind of tolerances the engine can handle.

Anyways, that's what I can think of right now, would love to get some help on this and maybe I can get started on some engine work soon =)


Laters,

Greg
 

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Discussion Starter #3
I've already gone through just about every post in the performance and mechanical forums, I was just looking for some more information and personal opinions.
 

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1. TGSI developed a bolt on turbo kit for the GT, don't know how well they do, this is my first and I'm going NA.
2. 1970 bottom end is pretty good. It has a fairly strong forged crank and rods. Rod bolts should be upgraded, but unless you find someone with a spare set they are willing to sell, good luck.
3. Stock compression is 9:1 in a 1970, newer motors are 7.6:1 (I believe)
4. Opel had a fuel injection system that will work with the CIH motors. I don't know what year they started, but I'd venture to guess the late 70s.
 

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Rods from other motors can be found cheaply and adapted and come with bolts. Even if the ARP bolts could be bought you wouldn't save much after figuring the cost of the bolts, magnafluxing, reconditioning and shot peening the stock rods. You'll have to have custom pistons made but you would want to do that anyway if your running a turbo. Besides, custom pistons cost the same or sometimes less than the stock units and they're MUCH stronger, as are the aftermarket rods.

Fuel injection was available only in '75 in the US. Works great on a stock or nearly stock motor.

-Travis
 

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Discussion Starter #6
Thanks for the input thus far

about pistons, Opel GT source has pistons for sale there, they've got overbore sizes, and a choice of compression ratios (7.6:1 or 9:1) Has anyone used these pistons? If they're any good I was planning on running the 7.6:1 ones, although it'd be nice if they were like 8.5:1.

Anyways, what are some good places that do custom pistons? and what are some swap applications for rods?


Thanks

Greg
 

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Greg,

Look at the post I've put up about superchargers vs turbo's. I think it will answer some of your questions... I'll add a little here.

If you're going with 9-15 PSI boost you MUST use an engine management system. The Opel (Bosch) FI computer, Mass Air Flow sensor, etc just won't know what to do. Our favorite is Haltech, but there are others.

The parts you will need are the FI manifold from a '75 or later CIH engine. You can also use the throttle body that came on the Opels. OGTS has the stuff. You won't need anything else from the an Opel because you'll use the stuff from Haltech. You'll also need a set of injectors from RC Injectors. (www.rceng.com).

Stock compression is "advertised" at 9.0:1 up to 1970 (flat top pistons), but in reality is closer to 8.5:1. From 1971 and on, the compression is "advertised" at 7.6:1 and that is fairly close. Both of these work fine with forced induction and you just adjust the boost and ignition timing accordingly. As long as you don't try and make "gobs" of HP, the stock cast pistons will work fine. (See the other post for "gobs" of HP.)

I hope that helps a little.
 

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The rods are for a Ford 2300. They are available in a few lengths which allows you to control your rod ratio and since you need custom pistons to match the rod length you can order them in any compression ratio and valve notch size. All for about the cost of rebuilding with stock parts.

I paid $225 for my bushed rods including bolts and they're rated up to 500hp by the manufacturer. I think that'll do:)

BTW, RallyBob has mentioned this adaptation before on the opeltuners and classicopels lists. I borrowed the idea from him.

-Travis
 

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Unless someone knows a "trick", you can't use the Ford rods directly on the Opel crank. The "big ends" of the rods are different (the small ends too, but the custom pistons take care of that.) So, you'll have to modify the crank and the rods.

An alternative (the one we use) is to get custom rods from Crower (www.crower.com) speciffically for the Opel. The rods are more expensive, but by the time you get done with everything else, they come out to be much cheaper. If you really want the best (only the best for racing), use Carillo (http://www.carrilloind.com/app.html) rods for the Opel.

How about it Rally Bob... any "tricks" you know to make using the Ford rods easy?
 

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It cost me $15 per rod to have them narrowed. I also specified Ford diameter journals when grinding the crank but they were close enough to the Opel that it didn't really matter. BTW, you use the Ford bearings which are cheap and readily available.

-Travis
 

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Travis pretty much answered your questions for me. The 2300 Ford rods are .013" wider, so either they must be narrowed .0065" per side, or the crank throws can be widened this amount when it's reground. The Ford bearing ID is .0004" larger than the Opel's, less than half a thou, so for a performance application using the Opel crank journal dimensions it opens the tolerances slightly which just about perfect for a high-po engine.

The availability and cost of the aftermarket Ford 2300 rods are much better than custom, which is why I've used them in the past. Rod bearings too, are much cheaper and racing bearings are available off the shelf. And off-the-shelf rod lengths can be had in 5.2", 5.4", 5.5", 5.7", and 6", although I usually use 5.7" in a racing engine, and an appropriately reconfigured piston. The pistons end up being much lighter (shorter), and I use very light .912" x 2.50" tool steel pins, as they have less weight to throw around with the shorter, lighter pistons. I also take the time to deign the piston for 1.5/1.5/3.0 mm rings instead of the heavier Opel rings. Above 9000 rpms, I've taken to using .043" top rings, as even the 1.5 mm rings will show signs of ring flutter at these extreme rpms, which tends to distort the top ring groove over time. Total Seal gapless secondary rings add a lot of longevity to cylinder sealing, I was seeing 215 psi cranking compression on a new engine and 28 races later still had 195 psi.

Also, on a 1.9, the rod ratio improves from 1.83:1 to 2.07:1 when using a 5.7 length connecting rod. The reduction in side loading on the piston is appreciable.

Bob
 

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Discussion Starter #12
wow, thanks for all the great info, got a few questions about things though...

What are some good companies that make custom pistons?

Also what needs to be done to the top end to handle the RPM's that you're talking about RallyBob?

I think what I'm going to do is head down to the local machine shop next week and get a rough estimate on what it'll take to get all the work done, balanced and all that good stuff. Before too long I'm gonna have an engine that redlines at 9k and runs 18psi of boost =P


oh, couple other things... is there anyone that makes a replacement steering rack? I haven't found one on OGTS, and haven't had much luck finding one elsewhere. Mine could at least use a rebuild, but I think it should be replaced. I've looked at the aftermarket racks from like flaming river, and their pinto rack seems like it'd be the right dimmensions to fit. Anyone else tried this?

Also, what was the outcome of the discussion of putting an S-10 tranny in a GT? I couldn't find the post about it. Just looking at 5 speed options cheaper than the Getrag that'll handle some power.


Thanks for all the info

Greg
 

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Some piston manufacturers are Venolia, JE, Ross, Aries, BRZ, Diamond, etc. Generally, Venolias are the cheapest and JE's are the most expensive.

For the rpms I'm talking about (8500 +), you MUST have roller rockers and a stud girdle, new rocker studs, plus high strength valves, springs, and retainers. Stock stuff will begin to fail as early as 7800 rpms (retainers for example). Your camshaft would also be pretty hairy to make power at these rpms, so it may not be a wise cam choice for the street. Turbos make fantastic mid-range power, and do not need high rpms for good power anyway.

Regarding the rack-and-pinion, most of the aftermarket Pinto racks are slow ratio for drag cars...about 4 turns lock to lock. The GT is 3 turns stock, so you don't really want to make the steering slower for performance driving (except for drag racing or Bonneville type stuff). Also, the critical rack length from inner tie rod to inner tie rod must be the same, or bump steer will be worse (and it's already an issue on a GT).

Trannys are a big issue with high powered Opels. The stock 4-speeds are marginal approaching 150 hp, the Getrags can handle about 200, and the ZF's (rare) can take 280-300. I'm not sure about the T5 tranny from an S-10, it's not as strong as the same tranny in a Camaro with a V8, but it should take some torque given the payload capacity of most trucks. Ratios are not so good however. Also, you will need to have a billet steel or aluminum flywheel made if you are going over 200 hp, and especially if you are going over 250 hp. I would not trust my legs to a cast iron flywheel designed to handle 100 hp. Clutch will have to upgraded, and rear axle and torque tube are VERY marginal at about 200-220 hp, even with a ZF or Quaife limited slip. If you are gentle and NEVER do burnouts from a standstill, or shift hard under power, the rear axle will be okay with upgraded parts. The torque tube shaft should be reinforced just the same, it's tiny.

Bob
 

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Discussion Starter #14
Well what I was planning on doing before when I was going to use the rotary, was to use the rotary tranny, and then use a Ford 7.5" rear end out of a Ranger. The ranger rear end is only 4" wider than the opel, so it shouldn't cost too much to get it narrowed a bit, plus there's quite a few options for differentials and disk brakes.

I was also looking at converting it to coilovers all the way around, I'm going to have to look a little more at the front end to get it figured out, but from just glancing at it, it looks like it would be pretty straight forward.

As for the T-5 I might just go find one out of a mustang or something and create my own bellhousing. Are there any flywheel options that will just swap in? And yeah I wasn't planning on trusting the stock clutch with 200ish HP.

As for RPMs, I was thinking a redline around 6500 to 7k at the most, it would be nice to have roller rockers though, I'll look into the valves and rockers and everything.


Thanks for the help,

Greg
 

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Discussion Starter #15
Almost forgot, is there anyone that sells a high volume oil pump for the 1900?
 

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Ironically this discussion came up just today amongst some Opel racing friends of mine. One wants to install a dry sump, but the reality of it all is that a properly operating stock Opel oil system if fine up to 8500 rpms, and only becomes borderline at 9000-9200. One of the guys (Tom Drake...GT-4 Opel GT) already has a dry sump (about $2500) and he has seen no change in operating temperatures, pressures, or horsepower. He said if he had it to do again, he'd just baffle the stock pan, and add an Accusump.

For road racing, baffling of the pan is required, but this is testamony to a good oiling system. If it ain't broke, don't fix it! Just make sure the bearing clearances are good, the timing cover is not worn, and the gears and oil pump cover are new.

There are German high volume oil pumps available but they are redundant for a 7000 rpm street engine, and they will consume slightly more horsepower than a stock pump.

Bob
 

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Discussion Starter #17
Thanks for all the info guys, I think I've got a pretty good idea of what I'm going to do now...


-rebuilt motor, balanced
-head ported and polished
-OGTS 'Torquer' cam (0.407" lift, 256 duration, hydraulic... don't see myself going over 7k RPM)
-Ford 2300 rods
-Chevy 305 dish pistons (found out that these fit great and give the right compression for a boosted engine, it's about a 0.060" overbore)
-custom made intake and turbo manifold... out of stainless of course :D
-either a T25 or T03 turbo
-Haltech E6K running it all

Going to do some research on the transmission, see if a T5 will work for what I want. Should go good tho, at least I'll have a big grin on my face :D


Greg
 

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If you are going to port the head, then install larger valves with upgraded springs and retainers. Porting the head with stock valves is fairly redundant, you'll spend a lot of time and gain virtually nothing in airflow. The stock ports are actually large in cross-section relative to the valve head diameters, so the valves need to get bigger to gain more airflow.

Regarding the turbo selection, you didn't mention what boost levels you are planning on running (but you did mention rpm limit). Check out the July issue of Sport Compact Car, they discuss turbo sizing based on engine size/rpms and intent (street/racing, etc.) Chances are you'd do well with a T28 or small T3, a T25 might be too small, but would boost rapidly in exchange for efficiency at higher boost levels.

If you want to discuss this further with people who know turbos, I know the author of that article as well as an engineer at at Garrett (both from other e-mail groups), and they helped me determine turbo sizing, trim, and AR ratios for a couple of 300+ hp turbo Opels. Of course, these required ball bearing center sections and new housings, not junkyard turbos, so they cost over 2k each. On the other hand, I picked up a Chrysler T3 for $30 and a SAAB intercooler for $75 at a junkyard. I had the center section rebuilt for $225 and basically the turbo was all new at that point. Building a high tech turbo engine with a ball bearing turbo, new intercooler core, silicone hoses, programmable ECU and higher flow injectors, fuel rail and pump will set you back $4500 and you don't even have an engine yet!

Bob
 

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Discussion Starter #19
Yeah, that'd be nice to talk with someone about it. what I was planning on running was about 9-14 psi, didn't want to get too outrageous with it. I thought I had that sport compact car mag, I'll have to go check. But what I had figured was like a T3 with an AR of around .45 - .6, it'd spool up when I wanted it to, but wasn't quite sure how it'd do on the top end.

That'd be great if I could talk further with your friend about it, would like to do this right the first time.

Good deal on the turbo, I've been browsing Ebay and checking out stuff there, you can get a T3 or RHB5 for around $200 usually that look in pretty good condition. Just trying to get around buying a brand new one, can't quite stomach that, the haltech is going to be spendy enough as it is.


Thanks for the tip on the head too,

Greg
 
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