Rob_DOHC

iTrader: (4)

Cheers for the info guys, and cheers for the input perry, i don't know how good my head is, i don't have access to a flow bench. But im hoping the dyno will tell me. If i make reasonable power at a boost level im happy with then i will deem it a good job.

Its not a bad copy of some of the nms heads i have pics of, i looked at one in the flesh and my ports are a very similar shape, albeit a little smaller due to smaller valves.

IMO the standard valves are more than big enough for the power i want, with out sacrificing off boost power, or torque. Sure bigger valves etc, as seen in the nms etc heads will come into there own at higher rpm/boost levels.

yes mate,


Rob,

crazycage

do you mean the .64 t25 flanged housing? or the .86 one only asking as i have the .64 sitting in the garage if you are on the .86 and want to try it out .

DazC

iTrader: (1)

No mate. It was due to go on Harvey's dyno twice but due to technical issues the engine was never run on it. It will now be mapped in car but I would have liked to have had a graph to see how much power it produced.

DazC

iTrader: (1)

Yes and no! It's a .64 T3 flanged housing. I don't think a .86 would be a good idea on a 1.6 CVH as the .64 is already quite laggy.

Rogeyboy

iTrader: (2)

What would a stage 3 t3, .48 and 55trim be like at them power levels? If crazycage's started to boost at 2600rpm thats not laggy, altho might be with the lower comp.

Crazycage when did your 260bhp cvh hit full boost!?

crazycage

no probs , the .86 t25 flange is more like a .63 t3 flange housing and the .64 t25 flange is like a .48 t3 flange housing.

crazycage

ill post the graph up later if i can find it, was a long time ago 2006

graph

Canada1

Nice graph crazycage.
Was the HP at the wheels or converted to crankshaft power?

On the head porting front - I had a race shop port my cvh head with the larger Burtons
stainless valves. The result was quite dissapointing when flow bench tested. A 15 cfm gain from stock ports and valves. (15 cfm at 28" depression) Still this 15 cfm would result in a 30 hp potential gain at 1 bar boost.

I then took it upon myself to carefully develop the head. Just enlarging the port and fitting the larger Burtons valves yielded 15 cfm (@28") peak flow. My brother had just purchased his own Superflow600 bench, and we decided to rework the cvh head.
We started with 2 standard castings, so we had 8 ports to experiment with. careful attention to port cross sectional area, and correct port taper we discovered much more flow. We did not even go to the larger valve sizes, but remained at 42mm.
The port size we kept 1 to 2mm smaller than the inlet gasket size to keep velocity high.
The cvh port being a swirl port requires some knowledge of what and where to remove material - a tricky port to properly modify.
In the end we attained 193 cfm @ 28" and 0.450" valve lift using factory 42mm valves.
This is a gain of 43 cfm from stock unmodified casting. Potential for an 80 hp gain at 1 bar boost level.

Cheers All

Rogeyboy

iTrader: (2)

Canada - Would one of your heads realistically see an 80bhp increase if running 1bar+ of boost, just by bolting your head on with no other mods to the existing spec?

Crazycage - that graph looks really good. Altho essentially they don't mean alot to me, all i look for is a smooth power curve. At what rpm was the turbo on full boost, judging by the graph?

Karlos G

iTrader: (4)

No, only at the point at which the head is the bottleneck and the rest of the engine is capable of processing the extra flow available by porting it.

You cant tell from the graph when it makes peek boost, or when it starts to spool, it's showing bhp and torque not boost.

Canada1

Hello Rogey,

The cylinder head alone with no other mods - probably not 80 hp maybe 20?
A 5000 rpm 1600 does not require 193 cfm inlet port flow.

However, a modified engine with an inlet manifold that was not a restriction, and
a performance camshaft, and a sufficiently sized turbo, then yes an 80 hp increase would likely happen. The difference between the "Big spec professional" builds, and the joe blow engine build is the combination of parts. Camshaft, headflow, turbo, engine management, all lead to high power at relatively low boost levels.

Rob_DOHC

iTrader: (4)

I agree with you on lots of points mate, its just in my case peak power and peak flow rates aren't nearly as important to me as low to mid range torque with acceptable but compromised top end. There are lots of cases of heads that flow more but actually make less power/torque in the real world in the right places compared to a head with a lower flow rate etc.

Any ho, cheers for the input every one. look like i have 4 turbo's to think about lol
One from the IHI range, stage 3 t3 (.48), GT2560 and GT28 that gary suggested.

Nice dyno Gary, and DazC when you get yours on the rollers i would love a look

Rogeyboy

iTrader: (2)

Karlos, cheers for the Info, No wonder i couldnt read from the graph where peak boost was, i thought there might have been a way of telling from the bhp/torque curves?

Canada - i see what you mean now. So even on a standard bottom end, running a stage 3 t3 turbo with a mild boost cam (kent24?) a correctly ported cvh would still see good gains?

Rob, I would guess the stage 3 t3 is the easiest option with regards to fitting. Whats the cheapest and most readily available?

Rob_DOHC

iTrader: (4)

IMO on a standard(ish) set up like that then no, especially if its MFI. What you could do, is run slightly lower boost. The gains become apparent when running high boost and higher power, where the engine needs more air. The more air you need the more a better flowing head is needed to match demand. Like canada1 has said in the past, its not all about the head, a lot of it comes from the inlet manifold as well.

But remember, you dont get something for nothing. From my point of view, bigger ports and valves lead to lower gas velocity which is especially bad at low valve lift off boost. The more power you make off boost the sooner you will come on boost.

Your right mate, the stage 3 t3 is the easiest and most available. But if i can get another turbo which flows similarly, but comes on boost 500rpm etc sooner then IMO its well worth it.

Think it goes against the grain a bit, most people are after maximum power, and are willing to spend money to get it, im after maximum drive-ability and im willing to pay for it, just whats important to the owner i guess other wise i would have stuck a t34 on it and been happy because that would definitely flow enough lol

Rick

You will struggle to stay responsive at 250, or more correctly, struggle to keep the boost threshold low. The problem with the CVH is it needs a shit load of air and fuel to actually make power, which means you can't go off typical compressor maps, you have to oversize the turbo.

A T34 is on its knees at 300hp on a CVH, where 370 is a walk in the park when on a YB.

Rick

Canada1

Rob,

You are correct regarding bigger ports and valves. The cylinder head we have developed keeps a very small port cross section (1.5 square inches) retains the factory 42mm and 37 mm valve sizes. Removing material only where it is beneficial to airflow is what we have done. This allows us to have a much more efficient head without the sewer sized ports many DIYers end up with.

For 280 hp you will require much more airflow than a factory unmodified head will allow.
Unless you find a turbo that is happy at 30 psi boost.

Canada1

Rick is spot on!

To make 300 hp on a cvh (with the standard poor flowing head) requires a huge level of boost pressure.
T3's and T34's are very inefficient at 30+ psi boost.
The YB will make 300HP at a much lower boost level.
It is not always about turbo flow - one must look at the turbo efficiency (or lack of) at high pressures.

Cheers

Rob_DOHC

iTrader: (4)

Would love to see your head in the flesh Perry, shame your a little swim away!

Cool, cheers. Well my last dyno was 185 @17.5 psi of boost, i think i could happily make 200bhp with efi, better ignition mapping and a different cam (mine was standard). This was on a stage 2 t3 so .36 exhaust housing.

I don't think i would be being too optimistic asking for 250 bhp with a larger exhaust housing, better than stock head with properly matched manifolds and 25psi of boost. Although my head was a DIY attempt, i spent A LOT of time researching and looking at examples, so genuinely think its a good improvement (not the best but better than it was).

But i guess we will see. I really only started the thread to see if people had used the GT2560 before and had any strong opinions of it.

Canada1

Hello Rob,

These cvh engines are as simple as engines get - no real magic. Standard Zetecs make more power because of a better flowing inlet port and manifold, and a much more efficient combustion chamber.
The cvh can be modified to outflow the standard zetec head, but we still have the inefficient hemi combustion chamber

Crazycage certainly has a spot on cylinder head (and inlet) to make 260 HP at only 16 psi boost.

You will find out soon enough how good your head and inlet are. Hopefully you will not require 25 psi to make 250 HP.

Cheers

crazycage

mike tanski from ferriday eng ported my head , and that was a flywheel fig ..it was 233@ the wheels.
just found an other graph for it from before it went to jamsport fot the management and cam ,made 160hp@ 6psi on the standard ofab and standard injectors with my inlet but standard exhaust manifold.

Rob_DOHC

iTrader: (4)

Thanks mate, lets hope so.

160 at 6psi still isn't bad going! think mine was 110 @ 5psi on mfi etc.

edit just looked, it was 105 @5psi lol

Canada1

Hello Rob,

As you can see from Crazycage's experience - 160 hp @ 6psi and your 105 hp @ 5 psi.
Even at those very low boost pressures appx. 50 hp difference.
I don't think I would be too far off saying 80 hp gain is in the proper head/inlet manifold when boosting at 1 bar is possible.

Cheers

Karlos G

iTrader: (4)

Gary's 0.48 housing would account for a lot of that power at low boost, this is the biggest restriction on a stock engine although the Ferriday head will of course have helped and then we have to bear in mind dyno accuracy say +/- an easy 25bhp.
My old stock engine and turbo for example made 155bhp @ 9psi on TOTD DD rollers but on another set at T&M Auto's it made 175bhp! lol

Would be interesting to see what I could make with a Stage 3 T3 or GT25 (or 28) as I have a very expensive NMS head and higher than stock CR.
But as with Rob I wanted response not max power so stayed with a Stage 2 T3.

Canada1

Hi Karlos,

Engine dynos are used here more frequently than rolling roads - thank God!
RR dynos have a tendency to be very generous and innacurate as you mention.

Looking for maximum low rpm response is a fine choice. But Rob has stated he wanted 250 to 280 hp. You are not going to get .36 exhaust housing to make anywhere close to those power levels.
I don't think Rob will be happy with a stage 2 T3. One is giving away far too much potential power.

Rogeyboy

iTrader: (2)

This thread makes for some interesting reading!

Rob - i c your point about driveability and response, whats the use of 300bhp/300lbsft if you don't see it until top revs, a nice even spread of power and torque lower down would imo make a quicker car on the road.

Karlos - i remeber speaking to you at a PF meet once about your engine, its certainly a good spec, esp with higher CR. Struck me as a strange idea, but as im getting more and more into and learning about turbo'd cars i now see the logic! Its funny how some people swear by low comp...

Ive just brought a stage 3 t3 for my standard comp efi engine... Bit worried i won't boost until 5k now!

Karlos G

iTrader: (4)

Yes your right a .36 will never get anywhere near that, 230bhp is really pushing it.
Ah yes was a while back now not been down there i ages!
Yes mate high CR is fine for upto around 300bhp so unless you want more why go low comp and lose low/midrange power and response?!

It wont be too bad, full boost of say 21psi by 4k latest on a stock head, cam and manifolds IME.
Whats your spec?

Rogeyboy

iTrader: (2)

Standard bottom end, head and cam. With stage 3 t3, scorpion system, full front mount and of course efi ofac management.... Stage 1 chip, so 12psi, Hoping for 160bhp to get me going!

Then onto stage 2 chip with uprated fuel pump and beiges with 15/16psi aiming for 180bhp & 200lbs/ft.

Would a cam or ported head make it boost earlier?
Maybe when the heads off, if i go for porting, i could get it skimmed to raise cr abit?

Rob_DOHC

iTrader: (4)

I agree, but you are somewhat ignoring the larger exhaust housing, different inlet manifold, cam etc etc. The 55bhp difference is not JUST down to the head @ 6psi. I don't think an 80bhp gain at 1bar is realistic, @14psi an rst makes maybe 160-170 bhp in standard form, so 240-250bhp from 1 bar with just a very good head and manifold isn't going to happen. Look at Karlos's engine, superb head, a good newmans cam high Cr etc and he is making 230 @ a lot more than 1 bar. Even with a larger exhaust housing i still don't think he would see 240-250bhp @ only 1 bar and i think he has a very well spec'd engine.

I do stand to be happily corrected! I think jam sport have an engine making 360 bhp at 22psi??? which has had A LOT of development and has a GT30. This i doubt is over 200brake @ 1bar.......

Rob,

Rob_DOHC

iTrader: (4)

Exactly mate, have a dig on here for D4_RST and have a look at his power graph. I would confidently say a good 200bhp rst would be faster in 90% of the driving situations you would ever come across compared to his switch on/off 300bhp.

This will have a few opinionated replies i think mate. IMO a standard cam will give you the lowest spool up time, you are making more power off boost therefore more exhaust gasses... which means a faster/sooner spooling turbo. Im sure this isn't true for ALL after market cams. A mild head would probably help too, but the larger the valves and ports the lower the gas velocity, and the less power you will make at low rpm and off boost.

To give you an idea, my car (before rebuild) was standard CR and stock bottom end, stock cam, stock head etc, with the obligatory scorpion exhaust and GRS front mount intercooler on mfi, with a stage 2 turbo this made 185 bhp @17.5 psi of boost, and whats more important 205lb.ft! with efi and a mild cam i think this figure would have been closer to 200bhp at the same boost. You may be better off with a stage 2 t3 for that power mate. We could always swap turbo's lol

Rob,

Rob_DOHC

iTrader: (4)

Here you go mate,
Where a cam, head and larger exh. housing etc would help is high rpm, my power and torque tailed off pretty badly, especially if you compare that to crazycages graph above, with a better head, cam, and inlet and larger turbo his just keep making power, pretty linearly to We make similar power off boost, i suspect this is due to the larger exhaust housing providing less restriction to flow, rather than cam/head etc, but after 2000rpm there aren't really too many similarity's lol

Rob,

Rogeyboy

iTrader: (2)

How do you think a stage 3 t3 would effect that graph?
Move peak power and torque further up the RPM range and stop it tailing off so suddenly?

Rob_DOHC

iTrader: (4)

I think you would see a 15-20bhp peak bhp gain if not more at the same boost pressure, the power would not tail off as badly especially if you had a different cam.

Where you make peak power probably wont shift that much, but i think you would be off boost for longer, so at 2000-3000 you would probably be making less power than the graph above.

Rogeyboy

iTrader: (2)

And adding a cam, would that make it boost later in the revs?

Rob_DOHC

iTrader: (4)

It depends on what cam really mate, a mild cam would probably help, a hot cam won't, im going for a cvh34 (probably) where as a piper t2 would really hurt off boost power.

Rob,

Karlos G

iTrader: (4)

I agree with you Rob with regards to valve sizes and cam profiles etc. just making everything bigger on a CVH will aid max BHP but cost low down response, but as Perry says you can modify the port shape to increase flow but not drop velocity then of course that is excellent and where the experience/knowledge of CVH head work comes into play and is exactly what I asked for when Karl Norris done my head.

Whats also interesting is that you made 185bhp @ 17.5psi and I make 231bhp @ 19psi, the only differences being my head, cam and EFI.

Rob_DOHC

iTrader: (4)

Definitely mate, i agree with that, my inlet side on my head is generally the same shape but with out the valve guides and rough casting. Nasty lips around the back of the valves were also removed and smoothed etc. Im hoping the 3 angle seats will help at low valve lift too.

True! The reason i referenced your engine was pretty much because of that, i think the difference would be much less if the only change was your head.

Oh well, lets hope my head isn't too bad lol shouldn't be too long until i find out. maybe a responsive 250 is achievable with a mild cam, efi and a turbo change, just hope my Cr doesn't hurt me too badly. My head and block have been faced so it could be a little higher than the 7.7/1......

My engine will be run in on the stage 2 turbo, and the cam that was fitted before, so the only real changes should be a new engine, efi, and lower comp. So perhaps a rr session when its mapped will tell me how good the head is.


Rob,

Canada1

This is certainly an interesting thread.

All engines are air pumps. The more efficient the airflow (entire inlet tract) the more power the engine will make. The cvh has a very poor inlet tract. Why do you think power output greatly drops around 5500 rpm?
Modified heads and inlets allow up to 7000 rpm potential.
Some people do like the 2000 rpm to 5000 rpm range.
I however like a bit more zip!
Even my Contour SVT (2.5 duratec 200hp) didnt start pulling hard until 4000 rpm.
It certainly was not terrible to drive.

The D4_RST example is probably the worst combination of parts ever assembled.
Too large turbocharger, and a very very narrow powerband. This build should never be mentioned as it is not typical of a propper build.

Why is everyone so concerned about 2000 rpm power levels?
Why not put a diesel engine in the car then?

Just my 2 cents.

Cheers

Karlos G

iTrader: (4)

Do you think the cam makes that much difference?
IMO Being EFI makes very little difference to max BHP because even on MFI you can take the timing to the point of det providing you have enough fuel of course.

Rogeyboy

iTrader: (2)

Karlos - What cam do you run?

Rob - The pics of your head (in other thread) do look awesome, and i wish i had the patients of you to acheive that sort of work/finish. Yours is a car im very keen to follow, progress wise - best of luck to you!

Canada - I don't think people want max power at 2k rpm, just as much power as poss to ensure a good turbo response time and smooth power curve to retain as much driveability as poss. I didnt realise head work was what restricted the CVH, it's something i'll def look into on my own engine!

Karlos G

iTrader: (4)

The Newman's RST CVH cam mate, Robs work does look good he has copied work from very good heads so I think he will see good results.
Nobody wants to wait until 4000rpm for boost because the CVH doesn't like sustained high RPM's, it generates a lot of heat and with our poor cam and lube situation will chew through a cam in no time, also rockers studs like to exit the head at high RPM's and of course general engine wear will be greatly accelerated if you have to spend all your time 4000rpm+, a nice 2500-6000rpm power band is ideal for a road going RST IMO, this is what I aimed for and what I have got and I cant fault it.
For reference I still make 220bhp @ 6600rpm so thats only a drop of 11bhp, not bad for a .36 housing.