sharpydoo

i posted here the other week about an 1984 Rx7 im interested it, it has a 2.8v6 from a 1978 granada, a few people said the engine is ****, but changing the engine could be a mission and a half, especially as im only learning. what options do i have to mod the engine for more power? and how much will it cost? and any idea what performance im likley to get from the standard V6, and how much i could improve it on a low budget?

any helpfull advice would be appreciated. cheers

J4CKO

iTrader: (1)

Get one of these, stick the motor in the RX7, dont bother with the old 2.8 lump, can be tuned but they are pretty wheezy old things and it would cost a fortune, much better to put the 24 valver in, asuming theres clearance.

http://cgi.ebay.co.uk/FORD-GRANADA-C...QQcmdZViewItem

NotoriousREV

If it's a fuel injected motor then it'll have 160bhp (if it in good nick) or about 130bhp if it's a carbed motor. Given that the original rotary motor only had 100bhp it should be quicker than the standard car (which was 0 - 60 in about 9 seconds). Don't expect it to be a fireball, but it'll be respectable.

As for tuning, don't bother. The 2.8's are expensive to tune and don't give much return. Bolt-on's such as filters etc. won't do much for power and getting the heads ported would only give about 20bhp.

As was mentioned on the other thread, get a 2.9 24V V6 motor from a Scorpio (off eBay for pennies), it should practically bolt straight in where the old 2.8 sat. The only hard part is fuelling. Probably best to do a search and see if anyone does a carb conversion for this motor.

sharpydoo

my only concern is i dont know enough to change the engine myself without help, and i dont want to spend loads on it, i know the engine is pennys but the fitting costs might not be, i really want this car as its very different, not your usuall looking 1st gen Rx7, but i dont want a plodder.

Shark Man

It's not "that" bad. With EFi it could push the old granny along at a fair rate of knots, even with the auto (160bhp and 0-60 sub 10secs). I think people in that thread may have been getting carried away with teh genIII RX7 with twin turbos which a completely differnt animal to the model you have.

With this particular year RX7, the engine was as asthmatic as the granny engine (0-60 8.5secs 13B engine @ 135bhp...wooo feel the power!! ). So in theroy, the v6 should be quicker than stock as it has a hell of alot more torque as well as BHP.

Now back to the granny engine, first is it efi or not? - that makes a difference. If its carb, you could swap it for a bigger holley/webber. Efi could be tweeked, and that age it probably needs a good tuneup anyway. With some time spent on flowing the heads, some decent cams and headers it could push past 190bhp (oh, and make sure the valve clearances are correct). Ebay is your best bet for bits, as new parts cost a fortune.

Transmission-wise it would benefit from swapping to the T-5 5speed manual, how this would fit is an entirely different issue. Alternative is uprated the auto by fitting a shift kit. Not sure these exist for the C3 box for v6 applications, so if you order one from the states make sure its suited to the engine (and not a huge v8 ). The box also has a vacuum modulator to adjust gear shifts, you can get aftermarket kits that can make the 'box more sensitive to throttle input. Another cheap fix is filling with good quality dexronIII fluid (instead of dexronII ) which can firm up shifts so it slur less between gears (it did with my BW35). Oh, and the brake bands are probebly overdue for adjustment by now.

Shark Man

Problem with this engine is they are auto only, and the ECU also controls the gearbox as well as the engine, so you need the entire wiring loom from the front end of the car to make it all work. So you'll need to dump the autobox too. And it's a ****-eyed bolt pattern, so you need a adapter plate made to fit another gearbox (has been done, but no off-the-shelf job though).

J4CKO

iTrader: (1)

There are load of Capri 2.8s running the 24 valve, cant imagine they are autos, best option would be to junk the standard injection and go to an aftermarket ecu and throttle bodies but based on what Scrapydoo has said I suspect we are running into big money and skills territory. Also, it would be interesting to see if Mazda provided a drivetrain geared to the low torque rotary, possibly a torquey motor might cause problems, then again Jap stuff is usually pretty tough and having seen some of the videos of them being thrashed on the net they look strong.

I suspect that even allowing for the torque it wont be any faster than the rotary, I think from what Scrappy is saying its a carbed version so 130 bhp, plus its a hell of a lot heavier than the Rotary unit originally fitted, so handling may be a little compromised, Capri's managed with it, well sort of, I would check it has uprated front springs to cope with the difference in weight, being one who fitted 3.0 springs to a 1.6, front end pointing skyward, the RX7 might be the other way round, nosediving due to lots of weight at the front.

I expect that the swap was for reliability and cost compared to the wankel which probably expired as opposed to performance. Might be worth just getting it running right then saving to put something else in it, I suspect that kind of car would be better with a revvy 4 cylinder rather than a big lump of v6. If the actual car is any good its worth the effort but they can be very nasty, I know where there is one parked up going begging if you want a project, it still has the wankel unit, you should see the fan on the thing, its like a helicopter rear rotor.

Shark Man

According to google, 13B is around 110kg, Cologne is just under 150kg. I thought it would be more than just 30kg

CrisPDuk

I'm sorry but that's bollox, there are adaptor kits commercially available to fit the Cossie V6 to any Ford RWD transmission.

Your best bet as far as the ECU is concerned is to bin the Ford one, and fit an aftermarket set-up, such as MBE, Lumenition, Emerald, etc, All of which can be made to run nicely with the original injectors, throttle body and sensors.

From the original post though I would be very surprised if the car in question is injected if the engine is from a '78 Grannie, The Capri was the first model to get the injected V6 (in the UK), and they didn't start appearing until the early 80's.

sharpydoo - A decent carb & a camshaft are probably the only way of getting more power out of it, but I'd have to question whether this is really the car for you if your only learning, I've been tinkering with cars for longer than I care to think, & I'd be wary of taking this particular project on.

On thing that hasn't been mentioned yet is weight, the good old iron V6 is nearly twice the weight of the alloy rotary it's replaced, if the front suspension hasn't been modified to suit the thing's going to understeer like a *******

Shark Man

It's not bollox. The 24v is pain in the **** to get running without spending thousands just on ECU/indction and adapter plates. Not ideal for a budget project.

Jacko mentioned and I've mentioned it...30kg. Those cast iron rotors must weight quite a bit.

Shark Man

<ting>http://www.gomog.com/allmorgan/engineweights.html

(German engine is the Cologne...NOT the Essex)

J4CKO

iTrader: (1)

Scrappydoo, best thing is to just get on with it, you learn as you go on these things, seeing what can be done makes me realise nothing (within reason) is impossible, its just doing it within the available time and money.