16v Conversion - Finer Points

[SPGTi 2]

Ok I am ready to give in and look at doing a 16v conversion on my road rally car. I have been searching and searching but getting more and more confused. I would have to keep the std plenum with no modifications and standard unmodified throttle body.

I am not sure if hybrid engines would be acceptable either, Blue Book H106d : Engines with more than one camshaft per bank of cylinders may be used providing that they were originally fitted with fuel injection and that the fuel injection system complete with plenum chamber and throttle body is retained unmodified.

I would then Megasquirt the engine so maybe later engines would have the edge (ie coil packs, a proper TPS, place for MAP sensor pipework, VR sensor in place etc).So the options

MI16, S16, GTi6, 2.0XSi, XU7 1.8 or hybrid.

 

MI16 - I am put off by oil surge, I know this can be got around but, being lazy, I don't fancy modding sumps etc. With the installation, the main issues are downpipe (re-angled with a plate or a cut and reweld job), radiator needs to be moved forward / dropped for clearance with inlet manifold.

 

S16 - I presume this is the same as MI16 for installation, but doesn't appear to have the oil starvation issues. The inlet manifold is different (??), how does this effect clearance with the rad ? The extra weight fom the iron block, is this really noticeable and would moving the battery / wash wipe bottle help counter this ?

 

GTi6 - Seems to be a tighter fit, esp around MC. Options, trim with grinder, use Magics "lowering mounts", change to pedal box (???). The GTi6 exhaust manifold is retained but you must either modify bulkhead or reangle downpipe (??) The downpipe, is this an 8v or the GTi6 one ? Using Magic mounts no mods are required (???). I think clearance issues with the inlet manifold are the same so rad needs moving forward (??). Same weight issues as S16

 

XSI - same as GTi6 ???, Is the head the same, so changing to GTi6 cams and exhaust manifold would give 160bhp ish ?

 

XU7 std - Lightweight option but would be expensive to get same performance as the above engines.

XU7 hybrid - using GTi6 head, inlet, exhaust manifold. Lightweight 150bhpish engine ?? Not sure whether it would be legal or not ?? I presume fitting issues would be the same as the GTi6 engine ?

 

Other general issues are sump to ground clearance on the conversions compared to the std XU9 8v. My sump guard takes a beating as it is and my ride is std to slightly higher than std depending on event. Would drive shaft angles be an issue, or is this just when lowering the cars ?

I already have grp N mounts and the 8v doesn't move about, would this be sufficient for a transplant or would moving to a solid lower bush be necessary. I don't want to have too much vibration / noise transmitted to the cabin as I need to be able to hear the nav and intercoms are not permitted.

 

At the moment I am favouring S16 or Gti6 engine. It is just the clearance issues / solutions that I am not sure on and whether the extra weight would be noticeable.

 

cheers

 

Steve

[jonnie205 1]

the gti6 engine sits lower and on lowered mounts will be even worse for ground clearance. I have always found gti6 engine goes in fine on std mounts no need to lower engine. Rad somtimes needs moving forward a small amount but not as much as mi. As your car is road rally i would go for the lighter and shorter mi16 engine, this engine will sit at the same height as your 8v so you can use same sump gaurd etc.

[wardy18 33 1 Cars]

Blue Book H106d : Engines with more than one camshaft per bank of cylinders may be used providing that they were originally fitted with fuel injection and that the fuel injection system complete with plenum chamber and throttle body is retained unmodified.

 

Does this relate to Rallying?!

 

Im gonna go to 16v and have just checked the Blue Book for Hillclimbs and they only restrict changing the block, everything else can be changed?!

[SPGTi 2]

Does this relate to Rallying?!

 

This relates specifically to road rallying.

 

Steve

[brumster 135 1 Cars]

MI16 - I am put off by oil surge, I know this can be got around but, being lazy, I don't fancy modding sumps etc. With the installation, the main issues are downpipe (re-angled with a plate or a cut and reweld job), radiator needs to be moved forward / dropped for clearance with inlet manifold.

 

I know your concerns, but am quite disappointed with the scaremongery that goes on around this. I suspect most of the people having problems are simply because they didn't do things 'right'. By right, I mean a baffled sump, running plenty of oil and doing the conversion 'properly' (ie. no bodging of engine angle). I get no oil surge on long sustained bends on a tarmac stage car running sticky CR311 X12. How you ever would get oil surge on a road car on road tyres, frankly, I have no idea. That's not to say I don't get low oil pressure at low revs - I do - but then my 8v did this too, and I was running 0W40 oil which I'm told is too thin. And the key things is it's not ZERO pressure (ie. cronic oil starvation), it's just LOW pressure - on braking into really slow hairpins I see pressure drop, but it's directly linked to engine revs. 20psi at 1500rpm for a few seconds I don't consider much to worry over.

 

As with all these things, if you're going to do something, I say do it right. That means a proper exhaust manifold and moving your rad rather than trying to cobble around it by running the engine at funny angles. But you knew that

 

Then again. S16 sounds a better option all round - let's be honest, I doubt the weight difference is anything to really worry over, and the generally-agreed consensus seems to be the head drains better. So all things being equal, the XU10 plan is probably better/easier.

Edited April 30, 2008 by brumster

[petert 591]

An XSi with a GTi6 inlet manifold, with cams, on aftermarket management is definitely the easiest install and best bang for your buck.

[chownr 0]

My two pence worth is that I wouldnt be at all concerned about surge on an Mi Road Rally car. Whilst It would be desirable to use the conversion with a proper Baffle kit Id say its not essential. Yes Ive spun a shell in my stage car but that was on moulded slicks on one of MIRAs finest hard long corners and to be honest having now run two MI engines I can say that oil pressure does vary between engines.

 

The first enigine seems to hold less oil pressure under load (despite a blue print rebuild) while the second holds its oil pressure much better. I can only summise that small differences in manufacturing tolerance and different sized oil ways and galleries play a part in this.

 

BUT as Ive said above the chances of surge in a Road Rally Car are negligible and if youre worried about them put a proper Baffle kit in and that would be more than enough security.

 

Cheap as chips way to get around 160bhp at the wheels. Couple it to a std Be box with a 4.4 final drive and youll be singing all night long

 

Rich

[SPGTi 2]

An XSi with a GTi6 inlet manifold, with cams, on aftermarket management is definitely the easiest install and best bang for your buck.

 

No go I'm afraid. See my 1st post for the regs.

Blue Book H106d : Engines with more than one camshaft per bank of cylinders may be used providing that they were originally fitted with fuel injection and that the fuel injection system complete with plenum chamber and throttle body is retained unmodified.

 

The other thing about Mi16s is getting a good one now that doesn't need rebuilding. How easy is it to scrap a crank ? as I think only .3 oversize bearings are available aren't they ?

My thinking for the S16 or GTi6 is that they are newer and everything is there to wire in 3D management ie coil packs etc etc. Has anyone got an actual figure for the sump height from the ground for these engines in a 205 compared to a XU9 8v ?

 

Basically I want the best value for money on a complete install, so that includes any new parts, modifications, ease of install and potential future problems. So for Mi16 that would have to include sump baffling and potentially for a S16 / GTi6 getting a new sump guard made up.

 

cheers

 

Steve

[taylorspug 7]

Oil surge in a road 205 MI on road tyres is shockingly easy on a longish bend. Mine would see the std oil press light on at times, and that was with the engine at the standard angle and terrible tyres. Put it this way it was something i had to be concious about at times. Im sure with a baffled sump etc the problem would be much better but the std setup is really bad.

 

The weight difference between the alloy and solid blocks is slight, but definately noticeable. The car doesnt change direction quite as quick, I also noticed increased shoulder wear and lower front ride height when i fitted my '6. However for the lack of oil surge and general better nature of the engine and management these are fair trade offs IMO for a road car. In any case ive made a few small adjustments to the suspension on mine now and the handling is more than restored.

 

For your car SPGTI id leave the S16. Looking at the rules you have posted above, you would have to retain the std flappy butterfly inlet which is a load of jank frankly. Id either go for the XU7 engine with the GTI6 bits on it, as they are externally identifiable as the same (which is usually all that matters), looking at the results people have got it would make good numbers and be reasonable weight wise. Either that or the full GTI6, i doubt you would have clearance issues if your suspension is higher than standard.

 

Also ive not found the need to lower the '6 engine to get it in, just reangle the rad and the exhaust manifold, cut and reangle the downpipe. Once you get the engine in the car you can decide what to do about the master cylinder clearance, as it does vary from car to car.

[philfingers 5]

Steve I'm working on my Mi16 install all w/e at SW address if you want to pop around. Doing the whole works with regard to extended pickup, spacer, 26t wheel and 52link chain etc etc

 

Phil

[petert 591]

I still wouldn't be put off using a complete XSi if a cheap engine came my way. The 205 exhaust bolts straight up, the head flows like gangbusters and it's physically the same size as a GTi6. It just needs cams to make it work.

Edited April 30, 2008 by petert

[SPGTi 2]

I still wouldn't be put off using a complete XSi if a cheap engine came my way. The 205 exhaust bolts straight up, the head flows like gangbusters and it's physically the same size as a GTi6. It just needs cams to make it work.

 

It was just the comment on changing the inlet manifold. So would just GTi6 cams give it a good power hike ? Would I have to change cam pulleys ? Would it be worth sourcing the GTi6 exhaust manfold or are they the same ? Or is it with the XSi exhaust manifold no reangling / choppping / rewelding is required to fit the downpipe. Basically if it got me 155ish bhp with minimal fuss I would be very happy.

 

cheers

 

Steve

[SPGTi 2]

Steve I'm working on my Mi16 install all w/e at SW address if you want to pop around. Doing the whole works with regard to extended pickup, spacer, 26t wheel and 52link chain etc etc

 

Phil

 

It is the Border 100 this weekend so will be getting the car ready Saturday. I will have to pop round and have a look though. I have been following your posts on this, anyway if I do source an engine I will probably need some help hint, hint

 

Steve

[petert 591]

It was just the comment on changing the inlet manifold. So would just GTi6 cams give it a good power hike ? Would I have to change cam pulleys ? Would it be worth sourcing the GTi6 exhaust manfold or are they the same ? Or is it with the XSi exhaust manifold no reangling / choppping / rewelding is required to fit the downpipe. Basically if it got me 155ish bhp with minimal fuss I would be very happy.

 

cheers

 

Steve

 

I'd regrind the standard cams before fitting GTi6 cams, as they really aren't much bigger and not worth the hassle of installing. Unless they were very cheap of course. Some XU10J4R engines have verniers. As the XSi exhaust manifold bolts straight up to a 205 downpipe without cutting, bending, chopping, welding, hacking, angling, etc., I just use it. I've done a standard XSi, just with new management and the torque and drivability if fantastic. It still runs out of puff at 6000 due to the small cams, but gets there in a hurry.

[SPGTi 2]

I'd regrind the standard cams before fitting GTi6 cams

Is there a PeterT regrind special ??? Does the CR need upping ??

 

Some XU10J4R engines have verniers.

 

is this the XSi engine ?

As the XSi exhaust manifold bolts straight up to a 205 downpipe without cutting, bending, chopping, welding, hacking, angling, etc.,

 

This is sounding more like my kind of conversion.

 

 

cheers

 

Steve

[Rob Thomson 6]

Steve, I wouldn't be worried about mixing and matching blocks, heads and inlet manifolds. As long as you're not running throttle bodies the scrutineers aren't going to give a damn.

 

The oil surge my (correctly installed) Mi16 gave in road use was shocking, enough to completely ruin the experience and make me dismiss all ideas I had about using the 309 for road events. To be fair, the little bastard didn't ever blow up and when I stripped it down everything was in good condition, but I just hated watching that needle drop every time it went near a corner.

 

Why do you want more power, anyway? You don't need any more than standard unless you've got an awesome nav, are a driving God, and are missing out on wins by just a few seconds.

[SPGTi 2]

Why do you want more power, anyway? are you a driving God,

 

Modesty prevents me from answering that

 

I scare myself now to be honest but it looks like, due to navigator problems, I will be doing less road rallying but doing a few more track days. The std engine is fine on smaller tracks but Donnington, Silverstone etc it is lacking especially as with the gearbox (you know the one I got off that dodgy bloke) I can hit the limiter in 5th quite easily.

I just want to keep it road rally legal but have a bit more poke for trackdays.

 

cheers

 

Steve

[philfingers 5]

It is the Border 100 this weekend so will be getting the car ready Saturday. I will have to pop round and have a look though. I have been following your posts on this, anyway if I do source an engine I will probably need some help hint, hint

 

Steve

 

You got a marshal sorted out? Could be available although would rather work on my new install! Help available for your install either way!

[SPGTi 2]

You got a marshal sorted out? Could be available although would rather work on my new install! Help available for your install either way!

 

think we are OK for a marshall, thanks for the offer. Will definitely need help on an install !!.

 

cheers

 

Steve

[James_m 0]

The oil surge my (correctly installed) Mi16 gave in road use was shocking, enough to completely ruin the experience and make me dismiss all ideas I had about using the 309 for road events. To be fair, the little bastard didn't ever blow up and when I stripped it down everything was in good condition, but I just hated watching that needle drop every time it went near a corner.

Agreed, and i run the full oil pump/sump setup from an S16 with the lowered pump pick up.

They dont all seem to be the same. Some people claim very low surge and mine is terrible.

I cant say id ever reccommend an Mi16 to anybody.

Doing it again id go for something iron blocked. The Xsi that Petert is talking about sounds sensible, cheap to buy and probably not from a car that has been thrashed to death its entire life/knackered which is always a risk with the Gti6 Mi16 or S16

[VisaGTi16v 1]

My Mi16, 3 years on 48r's then 3 years on slicks with just a pts baffle doing tons of sprint, 95k+ old engine, no issues, I am fitting a PeterT extended pickup and deeper sump now though just to help it out a bit

[Miles 331 1 Cars]

Bearings you can go down further than .3 on teh big's but not the mains AFAIK,

But they do surge but not too badly on road tyres, mine managed a full Race season before letting go at Thruxton but that was down to a Big end bolt, surge was mainly very bad at Oulton park's Harpin, other than that not too bad

[SPGTi 2]

Thanks for the input.

 

OK looks like I am favouring the xu104JR (Xsi) engine.

I take it this fits exactly the same as the GTi6 engine. Does anyone have any actual figures of how much lower the sump is too the ground than a std XU9 8v ?

Cams : what cam recommendation. It will be on std plenum and throttle body but with mappable fuel/ignition.

What CR does this engine run as std and will it need to be upped with more aggressive cam profiles ?

I presume that you can change the pulleys to 306 Rallye type if it had a/c or power steering.

Does it have a tin sump with any baffles / windage tray as std ?

Is it the same engine that also had an auto box ?

 

cheers

 

Steve

[jonnie205 1]

why not go for a gti6 engine? i can see the advantage of the xsi lump steve apart from being cheaper

[SPGTi 2]

why not go for a gti6 engine? i can see the advantage of the xsi lump steve apart from being cheaper

 

Now you've said that, I don't know. The inlet manifold on the Xsi engine looks a bit smaller, I can't remember whether this fits without radiator mods. I suppose if a GTi6 engine came at the right price then that would be a better option as I wouldn't have to mess around with cams etc. Looking about you do seem to get the XSi engine at a better price with low miles compared to the GTi6.

What have you got at your place to tempt me Jonnie ?

 

cheers

 

Steve