as the tital said im thinking about doing one ov them but what i want to ask is whats the power ov them both? which one is better bang for ya buck?

and for the zvh what do i need to build it ie parts coz i cant find a desent website that shows me what i need

cheers

 

ZVH's can be good but the general view on them is there is a LOT more ŁŁŁ needs to be spent to get it to the same level as a CVH.

A lot of people also say the CVH revs a lot better. To properly build up a ZVH it also to be a proper job needs custom cranks etc.....pricey.

As for ZT's theres not much mention of them that ive heard. CVH all the way for me

 

so ud recomend a rst engine? whats the bhp on them

 

CVH's are a lot cheaper to get big power out of. Obviously some people prefer ZVH's and alike but i think you will find the majority will say CVH.

Standard they are about 135 Bhp.

 

cool i shall put that in to consideration cheers

 

Just found this mate, a current thread. Enjoy

https://passionford.com/forum/viewtopic.php?t=199701

 

like safechav says,zvh pricey and problematic,more work than a woman on pmt, zt, easier way to go if youre gonna outta the two,helps if car is designed to take zetec lump cos then you got more mods if not.cvh tried and tested for many a year with turbo,www.zetecturbo.com www.zetecinside.com got shit loads of info as there may be in tech essay archives on here,if you wanna speak to some1 thats done the conversions then find avinitlarge on here on an evening(avinitlarge is user name)good luck whatever you decide

 

I had a ZVH and never had a problem with it mine was 240Bhp, pulled like a train, although i'd personally not have a high powered FWD again as it was a nightmare in the rain !!

 

CHEERS
what modds did u do or was it just a normal straight zvh? coz that would b plenty ov power that im after coz its only going in a fezz

 

reet cheers for ya help and iv decided to go for a rst engine with a big intercooler and a loverly turbo t3 i think, cam it and chip it hopfully that ull do for the fezz 200ish bhp i hope or is that wishing

 

I hate the CVH engine, Go for a zetec, A but more work involved though

 

What a load of bollocks. They are not cheaper to get "big" power out of. Name me one aspect of a CVH where it is tecnically superior to a zetec???

 

Thicker bore walls as tested by Karl Norris and a better rod ratio as standard more suited to turbo charging or high reving .

 

Have you got the figures to back this up? Or is it just parrot speak? What is the bore thickness??? What is the rod length of a cvh? If you could come up with the rod length we could d the maths and find out if it really does have a drasticaly more suitable rod ratio!

 

Using the specs for the cvh 1600 i could find off the net I have worked out the rod ratios for both engines

CVH 1.65

zetec 1.58

As you can see the ratios are not all that different!

From this we can see that the cvh may have slightly lower piston / bore side loading, but bore wear has neve been an issue on a zetec so no advantage there.

Rod length can effect cylinder filling at different rpms and there for ignition advance figures and camshaft choice and will also effect torque characteristics, but the difference between the cvh and zetec rod ratios will simply not have that much of an effect.


As for bore wall thickness... if zetecs are not cracking bores at 400 bhp i cannot see it being that much of an issue. Bore flex and cracking is not simply effected by bore thickness. I think you will find block design and structual rigidity is has a lot to do wih it!

 

Can you just inform me which bit of what i said is apparently bollucks?

I didn't actually do a lot of pin pointing in that.

But i do ask you this, why are there such a shortage of ZVH's & ZT's compared to CVH's if im talking bollucks.

 

I got 1.66 for the 1600 CVH and 1.55 for the 2000 Zetec.

CVH

Stroke - 79.52mm
Rod - 131.9mm

Zetec

Stroke - 88mm
Rod - 136.2mm

I agree that the cylinder dwell will not have that much of a detrimental effect at TDC but it can still have a difference. The Zetec is drastically helped with the reduced dwell time at BDC in a turbo application.

What are your views on adverse acceleration/deceleration (and thus increased loading/stresses) on the pistons/rods at TDC and BDC?

The block thickness was inspected by Karl Norris while he was at Jaguar. He disected a CVH and Zetec block to compare them. I don't have the exact figures but I remember at the time the CVH was around 1 point something mm on average thicker than the Zetec.

Bearing in mind, the Zetec is a CVH with a few modifications and a 16v head, the Zetec should technically be better although if I was to build one, I personally would like to ditch the crank and rods for something more like the CVH rod ratio, or maybe even higher.

P.S I was only naming 1 aspect where the CVH is technically superior to the Zetec.

 

The "CVHs are cheaper to get big power out of" part. All the supposed big bhp cvh's seem to be around the 300bhp mark (which is good for an 8 valve 1600) but seem to have a lot of money thrown at them. You have to spend alot of money/time on the head.

Now, i can take a stock 2ltr zetec and get nearly that horsepower out of it with a decomp plate (and the right turbo/manifolds)!

So tell me which one is going to be cheaper?

There are more cvhs because they come from the factory like that
They are in the car and already have a turbo bolted on. Swapping for a ZT takes too much effort for some people.

 

You are right. 1.659 for the CVH. My spreaadsheet was cut at two decimal points with no rounding.

I think you will find the zetec one is right for the later black top engine. They have a longer rod and shorter piston deck height than the early engine. The h beam rods and forged pistons that i use are from the states and out of the later engine. They go straight in the early engine and give it the same rod ratio so that was the specs i used.

The smaller rod ratio of the zetec makes my life easier when it comes to mapping a turbo converted one as it means that the cylinder pressures are more quickly reduced after combustion and which helps in the fight against detonation

Not sure what you mean by "Zetec is drastically helped with the reduced dwell time at BDC in a turbo application". Could you expand on it for me.

Short rods have a higher axial loading at TDC and BDC so i guess potentially more bearing wear.

Nice to find some one that can back up what they are saying rather than make random A is better than B coments to go along with the crowd!

 

mm imteresting so in a short answer what the specs say that the zetec it the better option or an i reading it wrong

 

it looks like the specs are saying the zetec may last longer and tbh imo i would go for the zetec, revs nicely

 

There is no answer!!!

Build an engine to suit what you want it to do.

 

Sorry, bad wording.

What I meant to say is that due to the smaller dwell time at TDC and BDC, a Zetec is helped a lot when it has a turbo charger fitted to it to help with cylinder filling.

 

i was confused there too but now i see what your on about. i agree

 

it all well and good saying that but i was asking for ur opinions coz u lot have probs done some thing like it before and u lot know more about zvh conversions than most web sites

 

Ok, there are so many different engine specs that deciding what engine to run will be very hard.

Generally unless the Zetec crank and rods are addressed, they won't like reving past 5k rpm where as the CVH will keep reving.

The Zetec head will flow more air than a CVH head but both will benefit from porting. A big valve ported CVH head has never been maxed out to my knowledge and then neither has the equivelent Zetec head.

ZVH is a pointless option IMO. They aren't a bad engine but why bother modifying the block to fit the head when you can just modify the manifolds to fit the head.

The Zetec based engines will be nicer to drive off boost and round town. The only other difference between the CVH and the Zetec engine is the CVH will keep pulling all the way to the red live where as the Zetec will slowly start to tail off, usually around the 5.5k rpm point. The Zetec will produce a big surge of torque which isn't helpfull for the gearbox or traction.

Cetrain things can be got round by different compression ratios, cams, valve ports and turbo sizes.

 

[quote="DazC"][quote="M1CH43L"][quote="DazC"]There is no answer!!!





The Zetec based engines will be nicer to drive off boost and round town. The only other difference between the CVH and the Zetec engine is the CVH will keep pulling all the way to the red live where as the Zetec will slowly start to tail off, usually around the 5.5k rpm point. The Zetec will produce a big surge of torque which isn't helpfull for the gearbox or traction.

[quote]


I would have to say this is utter tosh. If you have ZT engine that starts to tail off at 5.5k, thats down to YOUR turbo choice, ign timing and camshaft timing/choice.

It is not a feature of the engine itself.

At the end of the day, the zetec has a better flowing head and a larger capacity so is always going to make more power with less stress.

 

On a forced induction engine, the capacity is irrelevent except for when off boost IMO.

Maybe on the later black top engines the power won't tail off as fasts as the earlier engines but from my experience (limited as I must admit) the stroke does play a small part in causing the tail off. From most power graphs I have seen they seem to produce all their torque between 3 an 4.5k ish then.

Of course I do agree that the turbo, cam, port size and ignition timing will all help the reving issue.

Prehaps I haven't experienced as many high power Zetec Turbo engines as yourself. From the bigger power engines I have seen, they all had new rods/crank and thought they had addressed the rod ratio.

 

The main problem that causes zetecs to choke at ~5000rpm is the head flow.. and very closely followed by the crappy erst turbo manifold and then the intake manifold.. standard stroke zetec will quite happily sit at 7000rpm (with appropriate valve springs!)..

As soon as you put a tubular exhaust manifold, decent intake and a ported head, they behave like a motorbike engine!

 

so you want to go from a 1.1 50bhp fiesta engine to a 250bhp engine

just buy a standard 1.6cvh engine

 

Interesting thread, both of them.

Why is it though the 1.8/1.9 CVH engines seem to make more power than a ZVH?

Thats just a passing comment butfrom what i've seen the 1.8/1.9 CVH's make better power with alot less messing about compared to a ZVH/Zetec.

Would anyone agree?