about building a 1600cc turbo on a carb

[weegaz22]

building a 1600cc turbo on a carb, it would be a carbed mk3 cavy engine, i can build the plenum chamber to bolt to the carb, but what i want to know is does the 17td manifold have the same cylinder stud arrangment? so i could use the 17td manifold? or am i going to need to cut and reweld the original? going to lower the compression with a 1 mm spacer plate and 2 head gaskets, the only thing i need to work out is how to get the fuelling near enuff right, im just really building this as a project/fuckabout for a m8 any ideas would be helpful

[Ben (lurk75)]

This idea gets banded about a lot, but i dont think anything has ever come of it as people normally decide that it isnt worth all the fcuking about and is a lot easier to do on an injection engine.

Good luck would be intresting to see.

[weegaz22]

thats the whole point of doing it you dont need a special injection system/ecu, probably need to change the jets on the carb but so what?, fair enuff it wont run as much power as a gsi turbo, but itll be a damn site cheaper to do, like i say its just a fuckabout/project if renault can build a carbed and turbo'd 5 why cant i do it with a nova?

[Ben (lurk75)]

lol im not saying dont do it just saying most dont ever finish, the Renault comparison is always made and then is the fact that they are probably one of the most unreliable engines ever built!

As i said before keep us updated and post some pics when your finished.

[weegaz22]

any ideas if the carb would be ok for the conversion though?, will i need to mod the exhast or will the td one bolt on?

[Chris_W]

I think you'll find the reason people don't do it is they don't put enough time into the research behind the idea. Injection is simple to do, but carbs are even easier! Ok, this is where the research comes into it, and if most people had looked into this I'm sure you'd see alot more carb'd turbo conversions!!!

Car 1:
The old Lotus Europa was a carbed turbo charged car. Now this car has got to be the car that proves how easy it is to turbo a nova! The car ran special 'turbo' versions of Dellorto's DHLA 40 carbs (twin 40's ;)), around the carbs it ran a special plenum chamber, and to control the fuelling it had a boost sensitive distributer and fuel pressure regulator. Now all of this stuff is still available, and with the appropriate inlet manifold would bolt straight onto a nova. All you'd need to do then is get a turbo and manifold sorted out (Courtenay is a pretty good option) and then fabricate the pipework to get from the turbo to the plenum of the carbs and your away, how easy do you want it! The only difficult part here could be locating the turbo versions of the dellorto carbs, I saw some over on mig a few weeks back for ?275 the set! But if you can't locate the carbs you can always get a carb specialist to convert them for you. Go on, this would make an awesome car, and the power would be pretty useful too! :D

Car 2:
The Humble Metro. Yup, this shitbox got turbo'd aswell, and not just the once, but twice! The factory saw the success that Janspeed had with their single dellorto 40 designed turbo conversion, so decided to have a crack themselves. When the factory did it, they used a SU HIF6 carb. Same principle as the Lotus described above really. The interesting point here is that they used a compression ratio of 9.5:1! Now read that and think about it for a moment. Low compression? What about it! MG quite happily rolled these cars off the production line without any trouble. The theory behind it was that the higher compression kept the car quite spritely when off boost, a normal turbo car is very lazy off boost because of the low compression ratio. MG did alot of work on their engines when developing the car, as on high boost the car would detonate. But once setup, detonation was non-existant, this is through the use of a modulator ring on the carb, thus creating a boost sensitive carb, and this when combined with the boost sensitive dizzy and FPR made the car have reasonable economy whilst still having a fair turn of performance.

Well there you have it, 2 very different cars, but the same idea applied to both. Personally I think I'd go with the Lotus method as it would be fairly easy to dump onto a nova, as for compression ratio thats something that is up for discussion. I mean most turbo tuners will tell you the way to power is to lower the compression ratio, and as they make their money from those sort of decisions I think it would be fair to believe them, but as nova engines are fairly cheap I personally think it would be worth trying it on a standard engine and see what you cane get out of it before it goes pop before investing loads of money in low comp. pistons and stuff like that. Anyway, I came here to give you some ideas and you should have that by now. If anything isn't clear enough for you post up what you want explaining and I'll see if I can answer it for you!

Chris

[Chris_W]

Could I make this any easier for you! Here's the link to the advert for the carbs from the lotus!

http://www.migweb.co.uk/forums/showthread.php?s=&threadid=34063&highlight=lotus

Chris

PS. If any mod reads this, might be worth making this a sticky topic as it seems to come up farily often.

[rgv_stu]

as chris said u need a carb which is designed for use on a turbo

the fuel bowl needs to be pressurised with boost otherwise under boost the mixture will lean out and cause death.

i disagree with mg spending a lot on developing the metro turbo engine.
basically it runs so low boost that it is able to run on a fairly high comp ratio. the gearbox was the weakest link and rather than uprate gearbox internals mg turned the boost down :roll:

the 1300 metro turbo only ran 90bhp iirc which is obtainable easily from headwork / carb /cam on a nova 1300. a bit of wind ontop should make for a nice car :)

[Chris_W]

The basic thing is you need a turbo carb. The turbo carbs have sealing rings in them that stop the petrol being blown out the sides of the carb under boost conditions. Also, the other problem you would encounter using a normal carb is that the boost doesn't let the petrol settle in the float chamber, thus making the car run lean.

Chris

[MC]

I did work it out, but try putting the 1600i head on the 1400 or 1300 bottom end. Drops compression a treat. I'll try doing some sums when I get time.

MC

[rgv_stu]

i had thought of that as the 1600 head seemed to have bigger chambers / head volume. also the bigger ports/ valves would be handy :)

[cornish]

Look out for my 1.4SR Turbo this summer ;)

[MC]

Logic tells you this.

Both the 1400 and 1600 pistons finish flush with the top of the block, so to maintain similar CR's the 1600 must have a larger chamber in the head.

CP ran a 1400 head on a 1600 at one point, and the CR was so high he couldn't turn the thing off, it kept over running.

Therefore the opposite must be true.

I have sat down and done the maths, and I think the 1600 head used on the 1200 block give about 7:1, the 1300 block about 8:1 and the 1400 about 8.5:1. Can't remember clearly, but If I had a haynes handy I could work it out.

Thought about trying it, but I don't like turbo's much, and have carried on playing with NA.

MC

[weegaz22]

I could probaby mate an r5 gtt carb to the inlet manilfold, using a custom adapter plate, get it rejetted for the bigger engine, anyone know where i can get the spacer plates to lower the cr? lookin at using an escort rs turbo unit, maybe even the r5s, any other problems i could encounter?

[rgv_stu]

MC

are all the blocks the same height?? i thought they were different but i must admit i aint tryed measuring

if so then the 1600 must have shorter pistons to fit block flush as all the ohc rods are the same part no.

anyone measured chamber volumes on the heads / pistons

[MC]

Can't tell you, but I'd guess you are right about the pistons. I've stripped 1.4's and 1.6's and the pistons finish flush.

MC

[rgv_stu]

im still thinking the blocks are different height other wise the old trick of 1200 pistons and rods in a 1300 block to make a 1400 wouldnt work.

as they would stick out the top , cus rods on 12/13/14/1600 are the same

if the blocks were the same height then pistons would be different heights to equal out the lack of stroke.

[MC]

It doesn't matter about block height any way. The key thing is that the pistons finish flush, therefore the entire squish area is in the head.

If you keep the same volume of squish area (the head), and keep using a shorter stroke, ie go from a 1600 to a 1400, then the stroke to squish ratio drops, compression ratio. So you can see that block height doesn't matter, as long as the piston finishes flush with the top.

MC

[novax]

I've only taken my GTE 1.6 apart so can't say for sure what the other pistons look like. On the Series2 engines (1.8/2.0 8v) the throw of the crank was the major difference to get the displacement, I'm guessing this will be the same for the 1.4/1.6

[locky]

If i remember correctly the 1.6 was stroked out by 8mm, from the 1.4! i think, cant quite remember but im pretty certain its that!
(dunno if its any help!)

[RobGTE16vturbo6]

not that it would be that great but...

a standard weber dcoe will take 4-5psi

thats from weber so maybe squeeze 6 psi with new seals?

[dav]

my 1.6 turbo is running on standard 10:1 compression with standard injection and a T3 and it runs 14.2 1/4. that proves you dont need to lower the compression. I've had it running that way for over two years. I previously ran a double headgasket but just decided for a change to c if it would work with out blowing up. Best thing i ever done. All this talk about carbs with turbo's there was a guy back home in belfast and he had a gsi nova with a group A cossie turbo, double gasket and lotus espirit dellortoes . This thing was stupid quick. It used to smoke its 17'' raffino's in 3rd in the dry!

[Paul]

Diggin up 18 month old posts :lol:

Wasnt til i checked the MIG link i realised!

[NovaNeil]

But Dav i've been told yours has been rebuilt a few times just like mine, cause the dam thing keeps blowing up.

the joys of forced induction.... lol

Neil

[Snowface]

i'd love to be able to turbo my little 1.3. Might get to 140bhp that way.

interesting about the carb's from the lotus'. I've know they had turbos' on carb's but waasn't sure how.

[dav]

It only melts coz i get so greedy with the boost!

[isrs]

is it cheap to do a turbo conversion? is there any where you could got to get a 1400 SR turbo'd?

[mowgli]

back in the late seventies, gm did a low compression 1300 astra. if the badge on the back did not have an S on it, the engine was 8.5-1. I would imagine the pistons are still getable, and to be honest, if you were to build a turbo motor, new pistons would be a bl**dy good idea.