BHP from X19 1500 engine

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mark220475
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Joined: June 29th, 2006, 9:51 am
Location: Folkestone, Kent
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BHP from X19 1500 engine

Post by mark220475 »

Hello all
In need of some help? I would like to get about 140/150 BHP out of a x1/9 1500cc engine to use on the road as a fun thing.

So far the bag of bits I have got are.

Ported and gas flowed head with 40mm inlet valves compress at 10:1.
Kent cam, fast road, vale lift 10.33mm, timing 35/67 67/35.
Up rated oil pump.
Half way thought home made inlet manifold to use fuel injection? Over all port length 9.5‚ so if it needs to be changed not a problem at the moment.

Bits I have got to get.

Forged pistons. But at what compress?
What rings for the pistons.
Balanced crank.
Check con rods.
Lighted fly wheel. But to what?
Exhaust. What one?

So the help that I am after is, am I heading in the right direction? And what else will I need?

Mark
Acki

Post by Acki »

Hmm you need weber carburettor :D

Supersprint sells harmonically tuned exhaust pipe :)
For Tipo etc.

Camshaft >310‚° ;)

Crankshaft from 1.4 or 1.6 OHC -> big lift -> 1581cc

Rods -> Uno Turbo Mk1 without cat (weight is lower)

8-9.000rpm are no problem.

When I built those engine for my brother I can you show pictures.
DavidzFerret

BHP me too!

Post by DavidzFerret »

Firstly I'm delighted to see this forum as I found the old GC website so informative and missed it when it was gone. I count myself lucky to have bought one of the last of the TC books, as they disappeared off the pricelist shortly after I bought mine. Thanks Guy for sharing so much knowledge and info so freely.

I'd be very interested in the response/s to this question, as I have read lots of webposts on the SOHC engine, and talked to a few people. Generally there is talk of greatly increased power but they aren't so reassuring on the subject of low-mid torque and flexibility. Also conflicting views on how big the inlet valves /ports need to be.

Since my X1/9 is a sunny day road car and I don't want it too peaky, I got hold of a Regata DOHC and 5spd, and have freshened it up including balanced, lightened f/w and a port tidy up as recommended in the book. Argenta (I think) EFI manifold and I intend to Megasquirt it, having done this to a Rover V8 with good results.

But I'm not starting the serious work of getting all the pieces in the car and working together, for another week or two. If I can get what I want by livening up the SOHC I would be delighted to have that information before I embark on all that work!
Guy Croft
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Post by Guy Croft »

hi Mark - we just spoke on the phone - and David, a warm welcome to new look GCRE.

I just wanted to mention I am rebuilding the 'old site' as a 'sub site' of this one, to carry the long sequence builds and articles. I cannot do sequence features at all easily here, but the Serif software on the other site is a breeze. Also gc prices etc, non-forum stuff, and it's accessible via the GC gcre parts list button (next to members) at the top of the form.

There is a big valve SOHC head prep on that site which will interest you, take a look to begin with, and Mark, you also need to read TC Cam fitting and dry building 'how to' in the GC V/W section (virtual workshop) to get a handle on piston-valve clearances and cam timing. See:

http://guy-croft.com/viewtopic.php?t=14

(that article is in the wrong section BTW, I need to move it to the engine building section)

As far as CR your motor can run with 9.6/1 or higher. best CR? Depends on fuel octance and how well the fule system is set up, let's say a good all round might be 10 - 10.8/1, easily achieveable only by fitting race pistons with a big dome, NOT ever to be attempted by milling the head down. We don't do that on race engines!

Read all the GC V/W posts - see what you can learn and then we'll go from there. I post info in GC V/W that is hopefully 'generic'. Kind of building up a 'race engine techniques manual' there.

GC
James Bowen
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Joined: June 23rd, 2006, 8:17 pm
Location: Brighton, UK.
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Raising Compression

Post by James Bowen »

Guy,

Why not mill the head? (within limits)

I notice that the 1300 big valve build SOHC you have on the other site, is CC'd to 28cc. Standard is about 34 - 35cc isn't it?

I'm assuming it may be to do with head reliability and heat management, but I'm guessing here. Would, keeping flat topped pistons improve the speed of burn, over more complex shaped domed pistons?

Regards, James
Guy Croft
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Post by Guy Croft »

OK

milling the head down to raise the CR..

I should have kept quiet, knew someone would ask me 'why not?'!!

My dislike of the practice might have a little to do with the problems (grief) it creates with the general architecture of the valve-head-piston region, the inlet seat to head face proximity and the cambelt tension, never mind the fact that you can only do it once and it doesn't make a huge difference to CR anyhow. Not if you burette it and work it out actually which few people even know how to do - or bother to do.

It also has to do with my periodicallly being asked to overhaul such a thing after it's been messed in that way, I'm thinking back to a Dallara Fiat sohc years ago, an 8v engine that took me weeks to sort out, clearances piston to valve, piston to gasket, spark plugs to pistons, pistons hit the head couldn't tighten the cambelt and on and on, nothing would fit & 5 full dry-builds with metal pared everywhere to the limit.

High comp pistons with intruder dome are not so bad. You have to have experience of what happens to the burn if the dome is huge. It shows up in high HC emission and a jump in specific fuel consumption.

The TC Fiat is the same, very dirty, harsh and thirsty over 11/1 - and 11/1 is easily high enough for 200 bhp on 2 liter 8v. I rate 11/1 as being the best top limit compression ratio (CR) on Fiat sohc normally aspirated and I've tuned a fair few top spec ones. Milling the head down can seriously upset the surface to volume ratio in the combustion chamber and reduce power too, which will only ever show up if you do two engines to the same spec and mill one and not the other, which I have done. Everything is a compromise.

Happens with all kind of heads. The back street 'pros' go to work and a year later when it's crashed all its valves the owner rings me, wants a 'price, mate' and then this awful sticks-and-strings hybrid turns up and the job is twice the size it was purported to be and the owner stands there with a very sheepish look on his face. 'Oh, why isn't it easy then..?' If I take it on, I start losing money hand over fist.

I'm expert at losing money. It makes me cross! (This was not by any means the case with the head below which belongs to an outstanding owner/driver but the picture is a good illustration of the problems severe milling can cause)

I'll talk about it in GC V/W another day. In the meantime I'll cross you off my Xmas list if you do it!!! (did?)

GC
Attachments
Vauxhall 1600 Nova, rally prep GCRE, head milled 3mm (not by me), right thru the spark plug boss, then dropped a valve....nightmare to restore and with weld repairs too, very borderline to do at all.
Vauxhall 1600 Nova, rally prep GCRE, head milled 3mm (not by me), right thru the spark plug boss, then dropped a valve....nightmare to restore and with weld repairs too, very borderline to do at all.
Nova head porting and weld dress.JPG (28 KiB) Viewed 9287 times
Last edited by Guy Croft on July 2nd, 2006, 5:30 pm, edited 3 times in total.
James Bowen
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Post by James Bowen »

OK guilty then!!

But I have paid for it in part by the some of points you've raised. Not least of these was the cambelt tensioner having to be sleeved. Also a careful dry build, using your last website as a guide helped hugely.

I do my own engine work, just passing out stuff to be machined (Like the head re-face....Ahem) The trouble is that I learnt so much doing it, that I want to start stripping the engine all down again, and start a fresh. I now know where I can improve.
Guy Croft
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Post by Guy Croft »

OK

you're forgiven James, see new GCRE.com is having an impact already!

GC
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