Xmt - Sarty's Xsara GTI6 Turbo

[petert 586]

I think it's more like making 300hp with 9psi as he's using DFW pistons.

 

Are you sure the DP manifold is twin scroll?

[allanallen 528 2 Cars]

In the real world does it matter if you made your 300hp target with 25psi instead of 15psi? Who cares?

A target like that could probably be done with a stock compression XU7 with just a turbo adaptor.

Wasn't there a Dutch guy here who made over 450hp with a stock XU10 and a decompression plate?

The main issues are heat management, crank pressurisation and soft valve springs. Oiling if you go with an Mi16.

Why wouldn't you care? Why use 15 or 25psi when 10 will do? Lower boost pressure will help with heat management and negate 'crank pressurisation', I wouldn't even consider valve springs being a problem?!

I gave my example from experience running boost with gti6 and mi16 engines, saying a stock xu7 will 'probably' reach his target is a load of bollocks.

 

Yes a dutch guy made 450hp with a decomp plate on an s16. S16s have a much more substantial piston than the mi16 and gti6 though.

[Tom Fenton 1,541]

I personally feel ITBs are unnecessary and over complicated for your goals. are they not often junked on pulsars and skylines in favour of single throttle body anyway?

 

Having been involved in building a 16v turbo I honestly wouldn't concern myself about boost being lost on overlap using N/A cams etc etc. a standard engine will make north of 270bhp/300lbft on 10psi, turbo dependant with considerably little lag. You want to worry about making it grip and go around corners.

Agree with the ITB comments. Not worth the hassle in my opinion either. Many more places for boost leaks, difficult to balance properly.

 

But given the ease of opening the LCA on a twin cam head I do think that is worth exploring as it is very much improved boost threshold and driveability for nothing!

[wicked 103 3 Cars]

Regarding the ITB; I would advise you to take a staged approach:

- Build the engine(1.8/1.9) with gti6 plenum and throttle first. The plenum is better than the Mi16 one and the throttle body is more robust than the crapy twin valve of Mi16.

Don't bother about the size yet, it's big enough for your engine.

- Fit a nice WRC kit on the car.

- Enjoy the car for a while and debug it...

- If you still have the energy/time/resources to go for the ITB, then go ahead...

 

Often project fail because they want everything at once and underestimate effort/time/money....

 

Regarding the cams; they do matter! Flow is everything, especially on a turbo lump.

Why would you fit cams on an NA to get 10% more flow? 150bhp -> 165 bhp. 10% on 300bhp turbo engine will add 30bhp... (<-10% is just a number here)

Next to that, you want to keep boost at moderate levels (~1bar). At those levels you will have a wider power band were your turbo is capable of providing the request boost level at reasonable efficiency.

The higher the boost, the smaller the power band. -> start digging into boost maps and you'll find it.... Also you'll keep the IAT in control and don't need a massive intercooler.

Next to that, you will get more back pressure from the turbo at high boost, because it needs more energy. That can cause reversion of exhaust gasses in your cylinders and make it more sensitive to knock. Knock is lethal on an engine like this.

 

Any idea on the power you want have and which turbo you'll pick?

Edited March 21, 2017 by wicked

[allanallen 528 2 Cars]

Just to clear up what I meant by not concerning myself, it was aimed at the cams themselves rather than the timing, as you say thomas, dead easy to adjust on a twin cam.

[wicked 103 3 Cars]

The idea:

​

Edited March 21, 2017 by wicked

[Type-R 3]

Allanallen I didn't mean intend that comment to cause any kind of offence or flaming.

It's just my personal opinion that making more hp per psi is as meaningless as

making more hp with less ignition angle or compression ratio. In the real world what matters?

Getting the type of power delivery you prefer, reliability, good fuel consumption, low running costs.

To me these factors matter more. I mentioned valve springs as the XU7 ones in particular

are soft and would start to struggle at high rpm with boost added.

 

As for cam timing there's a Vizard book (can't remember which) where he explains how to figure out what you want.

It goes on about balancing pressure on both sides of the cylinder, generally the charge won't blow out of

the exhaust as it has a restriction there, so there's pressure on both sides. With a supercharger it will though.

But basically turbo cams work out pretty similar to NA ones, but with wider LSAs.

Edited March 21, 2017 by Type-R

[DrSarty 90 1 Cars]

I know I often type too much, so I'll try and keep this brief. Your excellent responses have given me pause for thought...

 

I've contemplated ditching the turbo idea and sticking with what I know (and like), N/A with ITBs. But I'm going to stay turbo, albeit via a simplified and probably easier - perhaps staged - approach.

 

Some key objectives then with related questions (perhaps considering this a design brief with basic solution ideas):

 

- While the Xsara in its current form is maybe a little ugly, I do want to produce a comfortable but rapid road car that I can occasionally track

 

- I'm tempted with a 'WRC look', i.e. a not too lairy body kit, but I don't know how much that'll cost. Ideas?

 

- A lot of YouTube videos, to me anyway, seem to show turbo'd cars with a lot of rather unusable power, i.e. lots of noise and wheel-spin. 300bhp seems achievable and usable, delivering a rather unstressed and reliable machine, but still with considerable grunt. I'm seeking lower rev-available boost and not too much perhaps past 5.5k. But how will that work with my Mi cams or standard J4RS cams?

 

- I'll drop the ITBs and go for a GTI6 inlet (regardless of Mi or XJ4RS head) and a single TB with twin-scroll turbo feeding it. Per PeterT's DP Engineering comment, is there a J4RS turbo manifold and what's different about a manifold suitable for a twin-scroll 'snail'? Is it just the flange?

 

- I'm still undecided on engine start point. The Mi route will potentially allow me to use the cams I have (see above query), but would give the potential oil issues UNLESS I provision for this (usual solutions or dry sump). The money saved on ITBs could fund the dry sumping. What might be dry sumping costs?

 

- But the XU7 bottom end with J4RS head avoids oil problems altogether, however what's the XU7-based solution advantage over the Mi otherwise?

- Are vernier cam pulleys advisable for inlet or exhaust, or both, regardless of engine choice?

 

- What are my Compression Ratio (CR) options please for either lump?

a} Specifically with the Mi choice I have the DFW (not DFZ, sorry) pistons which will give what CR, and what's a good cam choice? (This question perhaps aimed at PeterT)

b} What CR would the XU7 b/e plus J4RS head give me? Do I have to do anything with a thicker head gasket etc using the XU7 route to get down from what I'm guessing might be 10.4 or even 10.8:1?

Something great is going to happen anyway, as the MkI Xsara is sat outside and is ready for its transformation.

 

As a project manager by trade, I am/we are clearly still in the analysis and design phase, and I'm aware that solutions can still develop/change during implementation, but I would like sound advice still which helps me/us reach a workable start point.

 

Please keep the ideas coming.

Edited March 22, 2017 by DrSarty

[DrSarty 90 1 Cars]

Here's the donor. It starts on the button, seems to be completely sound chassis-wise (no rust I've found), is a little dirty, has s*itty Lexus rear lights (clusters) - that need replacing *help me please*, a worn driver's seat bolster and a faded white gear knob, and everything works:

 

 

[Anthony 1,003]

Pretty sure I've a gearknob kicking around you're welcome to.

 

RS head has same chamber size as XU7 head, so CR will be 10.4:1. I have a thick copper headgasket here to drop compression if that's of any use - certainly I'll never use it.

 

Lights aside, that Xsara looks pretty tidy too - sounds like you did well assuming that you bought it blind off ebay

[jackherer 543]

has s*itty Lexus rear lights (clusters) - that need replacing *help me please*

 

I just found a pair of rear lights Rich, they look fine except the bulb holder clip on one of them is snapped but that will be easy to sort.

[jackherer 543]

BTW did you know Citroen UK commissioned a company called Cituning to make two Xsara WRC replicas back in the day so they could leave them at various dealers to promote sales? They didn't look bad, on the outside at least, but you can definitely do better.

[petert 586]

A twin scroll manifold has separate ports in the flange. ie 1-4 and 2-3 equal length pipes. Thus a twin scroll turbo on a single scroll manifold negates any benefits.

 

An Mi16 with cams as suggested with 9-10 psi will make 300hp easily.

 

You'll need a vernier on the exhaust cam. If you use my Stage I cam, use a #3 or #4 inlet pulley.

 

Lubrication has been well documented. Choose whatever level you need. Certainly dry sumping will unleash even more power.

Edited March 22, 2017 by petert

[pug_ham 244 3 Cars]

This is an interesting project Rich, nice to see you've returned with something slightly off kilter from the norm.

Assuming the Xsara gearstick is the same way as the 306, I've a five speed gearstick from my old 306 hdi that should bolt straight in if you're interested.

Have a look at the Xu7J4P engine more closely, you could find it already has verniers fitted and I don't think it's been mentioned before but the sump is basically an unwinged version of the GTI-6 trapdoor baffle set up.

 

PM me the chassis number & I'll try to get the spec / build sheet off service box for it to see exactly what basis you have as a starting point.

 

g

[welshpug 1,657]

you are correct Graham, cam pulleys are adjustable on all of them just like J4R and RS, different lobe centre angle from different hubs, outer part of the pulley is the same.

being a vts it likely has AC so an alloy sump, even the steel one is shown as being baffled, similar oil pump baffle to the gti6.

Edited March 22, 2017 by welshpug

[petert 586]

Down under you'd never be allowed to put an XU9 in a later model car, as they deem the emissions to be inferior.

[allanallen 528 2 Cars]

Allanallen I didn't mean intend that comment to cause any kind of offence or flaming.

It's just my personal opinion that making more hp per psi is as meaningless as

making more hp with less ignition angle or compression ratio. In the real world what matters?

Getting the type of power delivery you prefer, reliability, good fuel consumption, low running costs.

To me these factors matter more. I mentioned valve springs as the XU7 ones in particular

are soft and would start to struggle at high rpm with boost added.

 

As for cam timing there's a Vizard book (can't remember which) where he explains how to figure out what you want.

It goes on about balancing pressure on both sides of the cylinder, generally the charge won't blow out of

the exhaust as it has a restriction there, so there's pressure on both sides. With a supercharger it will though.

But basically turbo cams work out pretty similar to NA ones, but with wider LSAs.

 

In this case it'll be achieving the OPs power goal with as little boost and advance as possible for engine longevity, it matters because either engine (mi16 or xu7) in standard form will simply not stand 15 psi +

[petert 586]

If you've got all the Mi16 bits, I'd still go that route. It's cheap hp. Adding a dry sump makes it bullet proof. Ideally from a handling perspective, you need the weight of the tank over the rear LH wheel. I realise that's not practical in a street driven car. Thus if you keep the tank and all the plumbing under the bonnet neat, then why not? It will add AUS$1.5-$2K to your bill. Pace setups come up regularly on the 2nd hand market and support is good.

[TAG 25 1 Cars]

The XU7 oil pump has the same pump baffle and sprocket guard as the gti6. As mentioned, ally sump with trap door. The pump sprocket is much smaller than mi16 and gti6 versions, and is slightly overdriven by the crank sprocket, meaning more oil pressure everywhere, and has the same 6 bar relief spring as the gti6 pump.

 

The XU7 has the same size crank sprocket as the mi16, and the full setup should bolt straight on to the mi16 (I plan on doing this, along with PeterT's extended pump pickup).

 

One point to note is that the XU7 sump does not have a drilling for an oil temp sensor (XU7 uses a dipstick type sensor that bolts into the block instead), but there is provisions for this in the casting, at the front of the sump, in a similar place as standard on the gti6 sump.

 

Interesting project, I look forward to the updates.

[wicked 103 3 Cars]

....

 

- I'm tempted with a 'WRC look', i.e. a not too lairy body kit, but I don't know how much that'll cost. Ideas?

 

- A lot of YouTube videos, to me anyway, seem to show turbo'd cars with a lot of rather unusable power, i.e. lots of noise and wheel-spin. 300bhp seems achievable and usable, delivering a rather unstressed and reliable machine, but still with considerable grunt. I'm seeking lower rev-available boost and not too much perhaps past 5.5k. But how will that work with my Mi cams or standard J4RS cams?

 

- I'll drop the ITBs and go for a GTI6 inlet (regardless of Mi or XJ4RS head) and a single TB with twin-scroll turbo feeding it. Per PeterT's DP Engineering comment, is there a J4RS turbo manifold and what's different about a manifold suitable for a twin-scroll 'snail'? Is it just the flange?

 

- I'm still undecided on engine start point. The Mi route will potentially allow me to use the cams I have (see above query), but would give the potential oil issues UNLESS I provision for this (usual solutions or dry sump). The money saved on ITBs could fund the dry sumping. What might be dry sumping costs?

 

- But the XU7 bottom end with J4RS head avoids oil problems altogether, however what's the XU7-based solution advantage over the Mi otherwise?

- Are vernier cam pulleys advisable for inlet or exhaust, or both, regardless of engine choice?

 

- What are my Compression Ratio (CR) options please for either lump?

a} Specifically with the Mi choice I have the DFW (not DFZ, sorry) pistons which will give what CR, and what's a good cam choice? (This question perhaps aimed at PeterT)

b} What CR would the XU7 b/e plus J4RS head give me? Do I have to do anything with a thicker head gasket etc using the XU7 route to get down from what I'm guessing might be 10.4 or even 10.8:1?

..

 

- A proper WRC kit with full respray will be more expensive than you think; lot of labor and full respray. Would park the idea until you've got the engine done. Think a couple of k..

 

- Usable power; save budget for a LSD, proper suspension and tires. That's half the story.

Next that; try to get a flat torque over the rpm range. Hence my remark to avoid high boost levels, as it will create a peaky engine.

With a flat torque it will give a more NA-like, controllable feel, because it does not kick in hard at certain rpm's. It tuned my 8v turbo boost level (rpm based) to have 230-ish lbft from 2700-5000 rpm. I could give it more in the 3k rpm ballpark, but would make feel like diesel. The result is a very predictable and easy engine and make my clutch last longer. (<- save budget for proper clutch)

The availability of boost is more dependent on the turbo and manifold you pick, than on used std cams or stage1 cams. Don't worry to much about the cams for this.

 

- Since your talk about cams and compression; note in the end it is about dynamic compression, not the static compression. With upgraded cams, you can lower the dynamic compression.

(This is also the very reason you need high static CR on wild cams in a NA engine; just to keep the dynamic compression in same ballpark)

Note that modern turbo engine have high static compression and pretty long duration cams. It's not only the modern engine management that makes it work...

 

- 1 engine is not mentioned yet; Mi16 head on the XU7 engine. Same bore; resulting CR 1:10.0; still oil issues, but better flow and possible use of cams.. Don't know if it will work with valves vs piston cut out.

Edited March 23, 2017 by wicked

[DrSarty 90 1 Cars]

All those lovely kind people who offered me bits I'm going to contact via PM. I know Jackherer's going to 'the south meet' on Easter Sunday (16/4) and I'm hoping Anthony can too? This is re lights and gear knob at the very least. I won't accept anything FOC unless you insist; we either trade or do beer tokens at least.

 

I'm narrowing things down you might be pleased to hear. Current thoughts are:

• No body kit mods, at least not for a while/ever, as they'll likely be mucho moolar
• Nicer 15" wheels, either in white or black with tyre profile per Welshpug's suggestions
• GTI6 front calipers and disks - I'll buy new disks but would like some '6 calipers please
• Refresh rear beam as necessary depending on torsion bars and arms etc already fitted, adding new 'uprated' dampers
• Emerald K6 ECU, new Sarty loom and GTI6 inlet and TB with 2nd hand (but checked) intercooler and PSA/BMW twin-scroll turbo - I need to identify a suitable donor vehicle type for the turbo and cooler ASAP please
• No dry sump initially, but does TAG's suggestion up there about using the XU7 oil pump - if I go Mi16 - make sense, at least as a starting point? I can dry sump later, possibly with a 2nd hand Pace jobby
• Likely Mi16 full engine to exploit the head, PeterT cam and pulley recommendations plus the DFW pistons for a sub 10:1 CR - Unless anyone can raise a totally convincing reason to use the XU7 bottom end with either the J4RS or Mi16 head (and thick Cu HG as appropriate). If I do XU7 B/E and Mi head, what happens with valves, CR and cams please?
• Exh mani to suit {a} the chosen head and {b} the turbo. Is there anything off the shelf please for either (J4RS or Mi/S16) head?

Timescale I'm estimating at 4-5 months. Budget estimate is £600 ECU / £800 mani / £400 turbo / £250 rear beam / £100 brakes / £300 mapping / Seat replacement or repair, lights, ancils and misc £200 = £2,650.

 

Sh1t the bed! - -

Edited March 24, 2017 by DrSarty

[Anthony 1,003]

I haven't really thought that far ahead, but I'll certainly try and make the meet next month Rich.

 

I've got a pair of GTi6 brakes here too along with a new boxed pair of disks. I'd kept them with the intention of fitting them on my clagwagon, but doubtful if I'll bother given the standard brakes are more than upto the job.

[Type-R 3]

Sounds like it's gonna be a bit of a weapon. I would be amazed if you got it all done for £2650!

Don't use a thick gasket, squish matters just as much with boost, 0.5-1.0mm is fine depending on the bottom end design and rev limit.

AIUI the pump itself on all the 16v XUs is the same but chain sprocket and relief spring is different - I may be wrong.

Have you already got the K6?

Can it do all the things like DBW and electronic wastegate control, boost by gear, anti lag (should you want it).

For injectors I'd use R35 GTR, for turbo and intercooler I'd probably use Mitsubishi Evo stuff.

A TD05-16G would be perfect for 320-ish, but there's also the Subaru IHI units that are suitable and

easy to find on ebay or some Japanese breakers.

I think the Evo exhaust manifold might be worth a shot if you want to try something different

and mount the turbo where the diesels do, at the rear of the block - 4G63 bore spacing is the same as XU/EW

Makes you wonder if a crank is adaptable.....

And I reckon half the people here could build a better manifold than DP..

 

Bear in mind you said you wanted traction and driveability and not excess wheelspin, so add LSD

and some suspension finessing to your budget - 300hp at just 5500rpm usually means a torquey engine

which will be harder to deploy with just 2wd compared to 300hp NA.

[petert 586]

I haven't seen any twin scroll Mi16 manifolds. I suspect you'll need to fabricate your own. This place maybe able to help you out with a turbo flange. I'd image you have similar suppliers in the UK however.

 

http://www.gtpumps.com.au/

[dcc 855]

I have a td05 20g, currently making around 340bhp on a 2.0.

 

Im swapping to a 18g for earlier boost, the 16g is too small tbh. For your applicated a vf34 is ehat you want