questions about engine mods

Options!

Am at the crucial discission stage myself and these are some of the options considered:

1) 1900 Standard - new rings and bearings, valve grind and new standard, hydraulic cam, 32/36 Weber and updated exhaust system. A sound used motor is an option here - just bolt it in.

2) 2.0 litre short block or long block(with 2.0 head) with the rest of the bits as above. This can be achieves at least a couple of ways a) Used 2000 engine ("Discontinued" by OGTS) so get lucky on the used market b) Bore the 1900 block 2mm and fit Chevy Pistons - see this forum. Needs a sound four-speed or Getrag five-speed.

3) Source a 2.2 litre CIH Opel engine or short block - call OGTS
Four-speed becomes marginal - requires Getrag

4) Source a 2.4 litre CIH Opel engine or short block - call OGTS
Requires Getrag five-speed

5) Fit a chevy 60 degree V6 with appropriate gearbox and diff.
-see this forum

6) Fit a Buick/Rover all alloy V8 with gbox and diff

7)Fit a Lexus or NorthStar motor g/box & diff to suit

8) Small block US V8 - Chevy/Ford/Chrysler/AMC/other GM

9) Big block US V8

10) V10 Viper or V16 Allison

Listed in order of expense/power/time to complete (or not) as the case my be.

There is a lot to be said for a near standard 1900/2.0 or 2.2

There are alot of things you can do for more power on the stock format. Better carb or carbs and more flow on intake and exhaust are a good place to start. More cam and going 40 or 60 over with your pistons helps too. Then again most of the stock motors had 7.6 to 1 compression, to me thats a must fix. The list goes on forever. I have gone pretty far with mine but I still have more money in the wheels and interior. I went at it with the idea that the car is rare and should be fun. I tried to not do anything I could not come back from. I also know that the geometry for the car is not the best so I left the weight alone. The motor in mine will be in the 120 to 130 horse range. For me, that is more than enough. I guess what I am trying to say is that you can always but a big block in it. However once you do it is hard to go back if you don't like it. Then again if I decide later I don't like how mine turned out. I imagine I can find a buyer for things like the new sprint or twin manifold pretty easy. Then I can put that 350 with the blower in it.

Ah yes, the quest for more power. Which brings up the old saying, "Speed is just a question of money, how fast do you want to go?"

Since you ask what mods can you do and keep it kind of affordable I will assume you can't afford to do any kind of V-6, especially turbo V-6, properly. Properly is the key word. You could do it half-ass and have a half finished project or something unsafe or undriveable, but what's the point in that.

Therefore I suggest modding the stock engine. You could swap in a 2.2 or a 2.4 easily or just build the 1.9 or punch it out to 2.0. A warmed over 1.9 can make 130hp easily on a single carb. 130hp will be very fun and quick in your GT. 150-160hp is a bit more effort but very doable out of the 1.9.

To swap in a V-6 will require a lot of fabrication. A turbo V-6 even more so. And the cost of the engine and installing it is only a fraction of what you will end up spending. Because once you put a really powerful torquey engine into the car everything behind it is going to start breaking. Time for a bigger clutch, bigger transmission, bigger rearend and driveshaft. Suspension will have to be upgraded all the way around, especially in the front to handle the extra weight. Brakes will have to upgraded to handle the extra weight. I'm not just talking better pads and slotted rotors, I'm talking bigger! Which will require larger diameter wheels to fit them.

Want a real world example? I built a Volvo rally car for a customer/friend of mine. Actually, we both built it. It started out as a normally aspirated 3.0 V-6 Volvo 262 model. With about 145hp in fairly stock trim it was pretty reliable and he won a divisional class championship with it. Then he decided he wanted more power! Now John doesn't do anything by half so we went for it. We put a TO4 turbo on it and a SAAB 9000, then later a Ford Powerstroke Diesel intercooler on it. Engine management was Electromotive Tec II. We were hoping for something like 250-300hp. Well, after tuning on the chassis dyno we ended up with 504 ft/lbs of torque at the rear wheels at 4000 rpm! At only 11lbs of boost! That's somewhere between 500-600hp at the crank! Oh my god is that car fast!
But guess what? Everything behind the engine started breaking and had to be upgraded. First thing to go was the rear end, and Volvo Dana 30's are not weak. So we had to adapt a Ford 9 inch. Then the tranny went, even though it had a Quaife straight-cut gearset. Broke two of them. So we had to adapt A Jerico dogbox out of a Winston Cup stock car. Along with that came a Quartermaster triple disc clutch and a Ford F250 driveshaft. And let's not forget the Porsche Brembo brakes on the rear and the Ford Group A Cosworth front suspension and AP brakes.
You can see a web album of the build up of the car here: http://www.printroom.com/ViewAlbum.asp?userid=oppositelock&album_id=124351

So my point is, if you can't afford to re-engineer the entire drivetrain then you can't afford to do a V-6 or V-8 swap properly. A warmed up CIH will be affordable and lot's of fun.

-Dave Clark

kyles1970gt said:

well, how much does the 2.4 run? would that be just a bolt in and go or is there still some fab work to do? l am trying to keep a lower budget, i am only 20, with a wife and kid, so theres where all my money is, so yea, all help would be nice.. Also, what size pipes are you all running for exhaust.. i was thinking on 2" dullies from the head back.. how about it??

Click to expand...

You would have to call Opel GT source for their latest prices. I am pretty sure that their prices will fluctuate according to what is currently available (new,used, or rebuilt). You can turn a 1.9 into a 2.4 with a lot of machine work (Bob Legere/RallyBob wrote an article for ClassiC Opels on how this can be done), but a 2.4 long or short block will probably be a little more expensive, but A LOT less headaches with the machine shop. Either way, a solid tune on a 2.4 should be over 160HP, that means 5-speed Getrag, 9" clutch, and suspension and brakes will have be upgraded to handle all this new found speed. Your exhaust should always be single pipe back to the resonator. I am assuming that this car will be street driven and not race-only, therefore, it is wise to stay with a slightly smaller exhaust pipe to enhance cylinder scavenging and promote low-end torque. A *V*E*R*Y* rough estimate is to add 1/8" per 25 horsepower over stock. (1"7/8 @ 90HP stock, 160HP is 70HP over, add 3/8", would make a 2"1/4)

That is a very rough estimate, but the point is that too little restriction in the exhaust and you will start to lose low-end drivability.

Now my question for the masses is, what to do with the rearend? Everytime a question of rearend strength comes up, the conversation always fizzles out. What can the stock rearend handle, and what is recommended for something in the 180HP range? any thoughts?

Just Glue a Gbox On

Many front wheel drive engines can be adapted to RWD with an earlier RWD gearbox stuck on the back.

That VW engine looks nice and powerful!

Also Mazda Mita 1800, Honda variants plus any other Alloy block/head Japanese motor that is about could be used.

I have settled upon a 1900 bored and stroked to 2,2 litres so that it looks original and will keep the auto gear box that is already in my GT - a GM Turbohydramatic TH180 as that was used in V8 Rovers so can take the four banger power with ease.

Am tempted by the Isuzu Nissan-Warner 4-speed auto as it has lock-up and overdrive which would be complemented by an Isuzu
torque tube diff with discs, limited slipand 3.9:1 gesr ratios.

That diff is no stronger than the stock GT diff but does come with limited slip and other good upgrades.