GTA project engine

[clee]

On a mission to get the most out of the Z7U ala 2bobanaconka tuning .
Most of the bits are here and the build should start sometime next week .Was aiming for Pod day but I feel it will be a bit tight so have not set that as a target .

I'm doing this with one of the Alpine lads who's real passion is engines .Most of the ideas are coming from him and he's just finishing off the second head .The exhaust ports/valves are having 95% of the reworking along with the manifold and run up to the turbo collector .Cam is sorted from Piper to a proven spec from a n other source from a few years ago .

Big Jim is on the case also and has just sent me these pics of the new pipework and downpipe .Really pleased with the outcome .Jim certainly knows his stuff
Divorced wastegate pipe to try and improve the crappy std setup .Single exit with silencer for track All on mocked up engine .


Adam L has supplied a fresh rebuild on the 60 trim 0.42 T3 mated to a .63 exhaust housing from Bloxsie .
Mr Scoff and I mapped with the bigger turbo on Weds night and now it's running 20psi on the std engine .Scoff will be mapping the new engine and we now have a fairly advanced starting point from the data on the old lump .
A real cross club effort to try and get the most out of the thing without spending thousands ..
I'll dig out some more pics and update as the build progresses ..

[Sparkie]

be good to see someone getting good figures out of this engine!

[paul b]

yeah,,,,,,go Lee....should be pretty awesome...with the added soundtrack of the Vee...ooooooeeerrrrrrrrrrrrrrrrrr ,,,,i've come

[clee]

Bits ...
Later Z7U engines had cross bolted central caps .This block had the meat in the casting but had not been drilled so off down to my friendly toolmakers

[clee]

Pistons ....0.050" off the crown and glass beaded .Need to dress the skirt .
I've got a brand new set of pistons/liners/rings but they are being saved for MK2

Lightened flywheels ,one from an Atmo so no timing teeth .If all goes well another engine is being built with added knowledge from this first one,so two wheels .

Water pump from 3liter engine .

[gtmatt]

nice work there mate , like your effort tuning the engine , keep us updated

[clee]

Bit of a delay ....
The liners out of the build block looked a bit worse than some others we had so decided to not to use them in favour of some better ones ....
Ahhh ,but, now then ...At some point ,probably when they went to the cross bolt design Renault decided to increase the liner base location diameter so when I go to fit them I've got 1mm slop This increase is noted in the engine build data for PRVs but does not mention the Z7U as being one of those affected .
So all you GTA guys out there take note ! Do not throw out old liners without checking the base location ...I feel I'm talking to myself somehow ...........

Just got the original liners back after being honed professionally to get rid of a step .So once the big ends shells get here I'll be on with building the bottom end .
Heads are done but not here until next week .

[clee]

Big ends shells here Mr Paul B via Renault France with a bit of RTOC discount

All parts here to start the bottom end build so it's clean clean clean over the weekend now all the dirty stuff is done .
Reworked turbo collector ...the std casting has a big lump on the large turn radius that needs removing and bias the flow towards the entry top .We are going to weld a divider plate to the collector that extends into the turbo itself to try and keep the r/lh flows apart as long as poss .

[i l k e r]

looking good Lee!

I've always had a soft spot for vee engines

[clee]

Re-worked heads .Exhaust valves around 2/3 mil bigger .Mucho material removed some added and removed again .



Std exhaust ports

[Andrew Cooke]

does the engine fire L-R-L-R-L-R ?

[MFaulks]

First post!

Hi Lee

Can I get that rain coat icon then please ..

Pics of heads on way thru wire as we speak, post away. Don't forget the guides haven't been finished to length yet. Like the way you are doing this thread .

As you mention the later blocks have the same spigot as the 3ltr, and obviously ran the smaller bore. This gives the advantage that these liners are much thicker than the std 2.5ltr turbo, and considerably thicker than the paper thin 3ltr (at the spigot, have had them develop cracks). Add into the bargain better heat retention in the cylinder for lower thermal losses.

As to the 3ltr pump, it's a much more efficient item than the std 2.5ltr paddle (corrodes due to cavitation) and brass so won't simply rust away either. So, it's the item to fit that’s if you don't go electric. You also want the 3ltr water divider as it gives closer 50:50 water distribution (feed) between the cylinder banks, the earlier 2.5ltr does not - favours the right side looking on the nose of the crank. The one area that does need taking care, and I have modified differently to what we are doing here, and that's get a better Y divider for the water exit from the heads. The 2.5ltr is poor in this regard, but the 3ltr is actually worse - have a look - right side exit flow crashes directly into flow from the left. I think we will need to change it. I'll send you some pics and you can post.

Hey, this is my virgin post - hi all!

[clee]

Closest I could get Martin

[MFaulks]

New poster! (less than 10 posts)

does the engine fire L-R-L-R-L-R ?

yes switches banks

[MFaulks]

New poster! (less than 10 posts)

Closest I could get Martin

ha-ha+ just need everybody else running away

[clee]

You'll get used to it ...they don't understand ...it's a GTA thing

[clee]

Things have slowed down a tad on this due to work commitments.Never mind , we are in no real rush and it's better to take things slowly after seeing a rather scary vid ( yeh, thanks for that Martin )
http://www.youtube.com/watch?v=_REQ1PUM0rY
Looked into the springs a bit and are going to be using some interference units so Martin is busy making them fit .Needs the spring seat area modding etc ....That should be about it parts wise .
Next to build the engine and mount it up on a spare subframe .Different starter is required and various bits of pipework ,belts and mounts need looking at when it's on the frame .Then pull the existing lump ,fit new ,iron out troubles ,run in cams and lump then remap ....
I think National day is probably not going to happen with the new lump .

[Chris Hebden]

What are you hoping to achieve with this Lee? The pics and research look immense mate! Well done to you

[clee]

Thanks Chris .
There is a power target ......But it must be achieved without spending £££££s .....300 bhp engine ,this is the Holy Grail for the GTA Turbo .
This will be more than the Europa cup cars but they were notoriously unreliable .Exhaust port and pipe runs up to turbo are the main restrictions .
Standard internals and apart from a cam regrind the rest will be Martins porting and valve work, 2 mil bigger exhaust valve and std but different model inlet . All the rest will be a mix of the best bits from other PRV .

There are no tuning parts available off the shelf anywhere as not many have tackled it and there is even less of a market for it if they did ...This is all to prove a point
Big power PRVs do exist but you're talking twin turbo and thousands upon thousands to get it done .There is one under construction in NI but that's being done with an open chequebook .

[clee]

Heads are finished at last and show pretty good results on the flowbench.Should pick them up tomorrow .
But now we know where the real power lies .....Cam lift ...the new regrind ones are the best we can get out of the std Z7U but we need more so on the look out for some Volvo b28, b280 or best ren30 2.9 for inspection and regrind .I did have a pair but sold them ages ago
The z7u regrinds are now in the bin it would seem . Hope we can flog them on ,they are a lot better than std but the higher lift is now a given .
Lots of other bits are heading that way as well .Newly ringed pistons now un-ringed
Oil control is key also so some Total seal 3 piece units and top ring but std issue 2nd .
Now then Mr Faulks ...we seem to be losing sight of that thing called budget

[MFaulks]

New poster! (less than 10 posts)

noo, all not blown... yet.... no I'll sit down and work it out but I think we will be ok, the real only major additions are the TS rings, and the double valve springs. The valve springs will be needed for high lift anyway, as the OE springs coil bind at 10mm lift anyway and hence won't do what we need

As you will be looking at longevity then you will want to have your bottom-end assembly static / dynamic balanced - flywheel clutch cover, rods pistons etc. Pistons you can do and just supply the lightest.

Just out of interest I was going back over old posts and files to try and find my flow numbers on the 3ltr heads to compare the 2.5 just done, and came across this... it's a works Pug prep'd GrA piston, didn't jump out at me before.... see the mod .. so oil control tis problemo as I have been worried, and borne out by the oil scrapper on the Eurocup piston I mentioned before, although that wasn't drilled with black holes like this one, possibly a bit excessive...

[Andrew Cooke]

I'd like to see the flow cuves

My head would love ~12mm+ lift (40mm valve), but it just isn't possible to get more than 10mm without either getting higher lift rockers made, and/or going to much bigger diameter followers. We didn't test the head over 12mm, but it was still picking up flow at that (~4cfm/mm).

Any pictures of the valve gear on that engine?

[MFaulks]

New poster! (less than 10 posts)

Hi Andrew,

Yes will do, measuring up all the cams I can find at the moment.

The 2.5ltr GTA version of the PRV Z7U has 44mm inlet as std, but on a 30 deg seat, I found that beyond 11mm lift the flow was limited by the discharge coef of the valve seat combo and didm't gain a great deal there after. However, the std turbo cam has around 7mm lift peak inlet and exhaust, and the Prima Racing cam (regrind) gives only 8mm, and isn't going to work that well on this application either.

Have pics of the rocker gear, what do you want to see, the setup, or side profile of the follower itself? I have measured up lift / duration etc with the std pad follower and ground flat followers and depending on the particular origin of the V6 cams can gain a few degrees and time-area, and slightly faster accel off seat depending on the cam position but about it - it's an asymmetrical profile (and changed bank to bank), and has the added complexity that follower that leads or lags the rotation of the cam (1-3 inlet follower lags the profile, 4-6 it leads, if you get my meaning) swaps from one bank to the other, most regrinds don't take this into account. However, I have found a roller rocker in a Renault 1.4 that matches exactly the PRV hardware and centers, and currently having a steel roller cam profile made up. Test with common cam gave roughly an addition 1mm of lift through rocker ratio. This may be the only solution but will bust Lee's budget so looking for other alternatives as well.

[Andrew Cooke]

I know almost nothing about the V6 engine, I remember my dad replacing the cams in his Volvo a few years back...

I'm not looking for anything specific, just wondering how it all fits together. I can see OHC, I guess it uses rockers, does it use 1 lobe for inlet and exhaust, or separate lobes? Does it somehow use a follower, or is it a bit like a pinto? Either way I bet the geometry is pretty complex.

When you flow the head do you use a correct sized cylinder bore? With and without inlet manifold? With my engine we didn't seem to gain anything with the big valve until the lift was pretty high, I think that what we gained in curtain area we lost in cylinder wall shrouding - until we lifted clear of the wall anyway. We didn't get involved in investigating further.

[MFaulks]

It's OHC, and uses rockers one per (12V version 2v cylinder). On the 24v version it had one per on the exhaust and one rocker for 2 inlets. This was done to fit the std head dimensions, and available hardware restraints. However, Lee's engine is the 12V.

Std inlet has been used 44mm, two versions, and uses the one giving best flow. The margin is too thin to allow a 45deg seat, so std 30 deg had to be retained.

Exhaust has gone +2mm and extensive port work.

Quick snap shot of the results (all measurements taken at 10inch depression, however can esay work this out to 28" if needed):

Bare port flow:

Inlet 121 cfm - no manifold fitted, some strange effects noticed at port entry, will investigate later.

Exhaust 88.5 cfm

E/I ratio 73% so on the money, but this is after extensive work on the exhaust, no real wonder this engine is a pint of mild!

With the header fitted and in revised configuration, flow-calming effect brought the E/I ratio up to 77%, where as fitted OE style there was a loss.

Inlet 8mm (valve fitted at peak cam lift) the flow dropped to 97.3 cfm
10mm 110 cfm
11mm 112.7 cfm

So slightly lower incremental than yours, but lift a smaller percentage of valve diameter.

91mm bore, 63mm stroke, each cylinder 416.66cc

[MFaulks]

pics as below

[MFaulks]

When you flow the head do you use a correct sized cylinder bore? With and without inlet manifold? With my engine we didn't seem to gain anything with the big valve until the lift was pretty high, I think that what we gained in curtain area we lost in cylinder wall shrouding - until we lifted clear of the wall anyway. We didn't get involved in investigating further.

Andrew, pics show the geometry best. But yes you are right same deal as you. Used a dummy cylinder correct size. There is little shrouding on the inlet and lifts away from the bore wall. But there is on the exhaust and this limits the size of valve and the gains as you say. A larger than std inlet valve probably would have some issues at low lift as you mention. As to the exhaust to gain further would need smaller stems and offset it. Simply more work than it's worth I think... will have to wait and see though

[clee]

It's dragging on a bit this so I've just been out and bought this instead
Scary thing is it would fit quite nicely
http://pistonheads.com/sales/1227490.htm

[Penfold aka The Dealer]

It's dragging on a bit this so I've just been out and bought this instead
Scary thing is it would fit quite nicely
http://pistonheads.com/sales/1227490.htm

F*ck me that looks like a monster, have you actually brought it?

[clee]

Two too many noughts for my pocket ...

[MFaulks]

Nice

Called earlier... both your manifolds are craked around the corner fold of the pipe flanges, too difficult to save, I'll send over pics, so u/s unfortunately. I have a short one that is good and I have checked it, do you have a long one? I'll give you a call when you're about.

[clee]

No manifolds left I don't thinks so anyway .There was that set on your heads and the only others are on the car .
Feck-it lets just get the rest built up and worry about them later .I will have three engines on the floor in a couple of weeks anyway so one of them may throw up a good set

[clee]

I now have all the bits ( well nearly ) to start bolting it all together
We still have an issue with the exhaust manifolds in that the new ones do not line up quite right to the head .
It all looks very promising .Martin has sweat a bit of blood on the heads so thanks for that mate
Weak points will be cam and hopefully clutch

[gtmatt]

your doing well mate , keep it up cant wait to see this engine complete , where did you get your shells for the bottom end from??

[MFaulks]

Thanks Lee, my pleasure, let's hope we get results we're looking for and that will be the important reward.

Need to spend some time thinking about the ultimate turbo spec, as we have modified so many things getting a baseline is going to be difficult. The whole performance and characteristics of the engine in terms of torque etc is going to hang on it. The engine should /will now more efficiently empty the cylinder, reduced pressure loss to the turbine inlet, but this will hinge on the A/R of the turbine housing determining the back-pressure. The over-lap time area of the cam has been increased, will give us increased blow-down, increased cooling of the exhaust valve and piston crown. So will want reduced backpressure to gain the advantages.

How are you finding the std engine performance with the .68 over the previous .48 turbine housing in terms of spool response, torque curve and go go go? What's the transition like from n/a to forced, and the mid-range torque?

We should be aiming for 350hp probably top limit and on the very happy side, but certainly over 300 . So we can work back from there and size up.

Let me know if you get the chance to check a different set of headers, thanks.

[clee]

We got on a bit more with this today .Mucho cutting and welding of exhaust headers mainly .There are still lots of boxes of bits lying about tho and some things have gone walkabout but there is light at the end of tunnel and I think it's twin-turbo'd
.48 turbine housing on a single std layout for this build but for the next generation we are pretty much convinced that two blowers are the way to go .

[Andrew Cooke]

yeah, twins would be nice

[clee]

It's the way forward .It still needs to be DIY 2bobanaconker tune so std headers upside down and pointing backwards or GTA N/As .Smallish T2 or more modern but common cheap as chips units will do . Any tips on what to look out for would be welcome all

Venturi used the PRV with twins for the 400 LM's .I've seen one in the flesh at Bruntingthorpe and reckon a GTA with a similar power plant would have it for brekky

[Andrew Cooke]

are you sure you're only looking for 300hp?

You just need to find a production engine around 1.5L and 150hp at your kind of boost, and snaffle a couple of turbos off them. Fiesta RS turbo maybe?

Why don't you use T3's and stick a couple of Escort RS turbo blowers on there, that'll leave the road free to fit something flash on in the future

[clee]

300+ is the target for this first build .Get the most out of the Z7U in a fairly std layout without custom headers etc .That will destroy the myth

400 + with the twins is very possible
Twins feeding through single cooler to single throttle body .Mr F will be able to do the math and very tech stuff and I'm going to learn how to weld ......Ali and steel

[Andrew Cooke]

I'd imagine that you'd be looking at 400hp at around 1 bar boost. So maybe a 45trim T3 compressor? I can't remember what an escort RS turbo uses, I think it has a .36 exhaust housing, so a reasonable starting point. It all depends upon what you can find lying around really.

[clee]

Std GTA is T3 with a .36 turbine and .42 comp so a couple of those instead of just the one Escort cossie T3 60 trim is a normal upgrade .
Martin was on about a Mitsu of some sort from a common source that are cheap and plentiful ,I can't remember what .
A bonus is that I now have a GTA breaker so I can mock stuff up on a subframe and plonk it in the remains and see what would work where as the plumbing and intercooling is going to take some thinking .
Trouble is my work is on the downturn so it may well take a while to find the funds but the upside is I'll have plenty of time to mess about and do it

[MFaulks]

All zee pips are now weld nicely, just as your mum would like'm

Blimey on the EFI manifold stuff , if anybody else wants one I have a couple, I could do with some nosh, petrol costs are killing me at the moment!

[clee]

Good stuff .Did you find the missing spacers ?

Yeh ,good price on the EFI .It's going to the States.One of Stunned Monkey's contacts .

[Andrew Cooke]

Std GTA is T3 with a .36 turbine and .42 comp so a couple of those instead of just the one Escort cossie T3 60 trim is a normal upgrade .
Martin was on about a Mitsu of some sort from a common source that are cheap and plentiful ,I can't remember what .
A bonus is that I now have a GTA breaker so I can mock stuff up on a subframe and plonk it in the remains and see what would work where as the plumbing and intercooling is going to take some thinking .
Trouble is my work is on the downturn so it may well take a while to find the funds but the upside is I'll have plenty of time to mess about and do it

A couple of standard turbos may well do the trick, measure the compressor inducer to see what trim it is
Are there any single scroll mitsu turbos? I don't know anything about them, you won't want twin scroll with the twins.

[clee]

Just had a sort out, found these bad boys ...Std GTA T3 .
42.50 inducer .

[Andrew Cooke]

That'll be a 50 trim then, you won't want anything bigger, coming in at the right type of cash by the look of things

[clee]

Just right for my wallet
I'm going to mock up something at the weekend .

[MFaulks]

Not had a chance to look yet, worked late the other night doing the headers down the workshop, not been out to the garage yet.

There are a couple of versions of the std GTA turbo compressor cover, want the larger one of the two, think I have some kicking around too.

The route to go will be block the internal waste gates, have a Y cross-over pipe between the headers and an external waste gate atmo vent

Will likely want more inlet flow than current balance, as the overall system performance from the point of exhaust mass flow will be looking very healthy indeed with twins. I think the 380 - 400hp could be possible. No silencers or through losses, and minimal inlet restrictions up stream of the compressors. Need efficient inlet charge temperature control, not what we have at the moment. I would rework the pistons to ensure the top ring isn't going to float off it's land through blow-by gasses trapped between the top and second ring, and would need further oil drain back. Probably end up moving peak revs up to 7.5 to 8k... the king is dead, long live the new king Project 2

[clee]

Mr F ..tech/weed in ass dept ...
Best get Mk1 done first tho ay
No rush ,we have all winter now .
I need to get the Red one out the way ..It all fires up and good pressure ,sounds sweet but have a water leak on the pipe at the back of the V under the turbo
All stripped out and ready to repair but waiting on a £3 bit of silicon from Dellboy....I might see it sometime in the new year ..................................
Or I'll see if I can find a suitable offcut in the factors