Lowering Compression

[averyaaron1979 0]

can anyone help me with a query i am trying to find out what 8v engine i have to work out if it's a low compression 1900 8v or a higher version. the reason i ask is that i am currently building a track toy that i am trying to get the compression ratio down to the low 8's. is there any reliable way of doing this as i don't really want to be cutting corners and trying to put two head gaskets together not with the abuse it shall be getting.

i am after the low compression to run a supercharger with bike carbs or bodies and need the low compression ( so i have been told ) to run the charger at 1.5 bar... can anyone confirm this??

the plan is to run my stripped out 309 hopefully mid 800 kilos mark with a 8v supercharged with an intercooler instead of a chargecooler as it shall all be placed around the front end and minimal pipe work to reduce drag.

i was going to plan to run it from a standard 1.9 box with a mi final drive.

 

any ideas or advice would be great or if i get told i am way off the mark i shall have to rethink the ideas...

[danpug 1]

If you can afford it then forged low comp pistons would be best. With that amount of boost and the right management i'd imagine you will be running good power so they may be your best bet. You can get your standard pistons machined a little but i don't know how much power they could cope with, vern on here is running 230-40ish bhp with machined pistons with no problems so far.

[averyaaron1979 0]

If you can afford it then forged low comp pistons would be best. With that amount of boost and the right management i'd imagine you will be running good power so they may be your best bet. You can get your standard pistons machined a little but i don't know how much power they could cope with, vern on here is running 230-40ish bhp with machined pistons with no problems so far.

 

dan thanks for that, what boost her running then?? i was hoping fo around the 200 bhp mark as i thought going over that would cause all end of trouble with reliability.

 

i may have to work out the amount that needs to be machined and get that done, i only wanted to have a little fun with the more exspensive material out there on the track days and wasn't hoping for a massive power gain.

 

i take it vern is running a sc on a 8v?? i am looking for ideas other than the old mi route.

what cam would be a good idea with a sc running between 1 and 1.5 bat then?

[danpug 1]

Vernons is a turbo conversion. With proper management you shouldn't need that much boost to achieve 200bhp and also you shouldn't need to go so low on compression. Not sure what boost vernon runs but i think it was under 1 bar? The turbo guys on here tend to go for the cam from a catalitic converter 1.9 8v, i'd assume it works the same way in a sc conversion.

[averyaaron1979 0]

Vernons is a turbo conversion. With proper management you shouldn't need that much boost to achieve 200bhp and also you shouldn't need to go so low on compression. Not sure what boost vernon runs but i think it was under 1 bar? The turbo guys on here tend to go for the cam from a catalitic converter 1.9 8v, i'd assume it works the same way in a sc conversion.

 

dan once again thanks for that, this is only in the idea stage and speaking with a friend who is mad as a hatter seems to think it would need a low 8 comp ratio, may be he was wrong on that fact..... i shall await the tech guys and hopefully this can be explained as i would love to put this all into practice and actually have some good fun with the car instead of lagging well out the back with her.....

[danpug 1]

Yeah no doubt the cavalry will around shortly and explain all!

[petert 591]

Check the three letter engine code:

 

DFZ - 8.4:1

DKZ - 9.2:1

D6B - 9.6:1

[snillet 1]

The DFZ (XU9J1) head on a DKZ (XU9JAZ) bottom will give 8:ish to 1 ratio. Quite a few run that setup here.

 

I also know a few that has machined off the XU9JAZ pistons and put them into XU9J4Z engines and turbocharged them, one of them is pulling approx. 400hp from the engine and the pistons seem to cope fine with that, the XU9JAZ pistons has a quite thick "crown" that can be machined without any problems.

[whizzer71 0]

The DFZ (XU9J1) head on a DKZ (XU9JAZ) bottom will give 8:ish to 1 ratio. Quite a few run that setup here.

 

I also know a few that has machined off the XU9JAZ pistons and put them into XU9J4Z engines and turbocharged them, one of them is pulling approx. 400hp from the engine and the pistons seem to cope fine with that, the XU9JAZ pistons has a quite thick "crown" that can be machined without any problems.

 

How much do you have to machine off the pistons to lower the compression enough ?

 

Tris

 

[TEKNOPUG 3]

Run standard compression with proper management for superior results (power and driveability wise) just be restrained with the amount of boost you run.

[snillet 1]

Run standard compression with proper management for superior results (power and driveability wise) just be restrained with the amount of boost you run.

 

When aiming för 200hp that sounds sensible, the ones i´ve mentioned have reached beyond that.

[Banjo 1]

Would it not be better to supercharge an mi for track work? As said with decent management standard 8v compression ratio can stay

[cyman 1 1 Cars]

Would it not be better to supercharge an mi for track work? As said with decent management standard 8v compression ratio can stay

[/quote

 

I have the D6B MI16 engine, i machined the pistons by 1mm from the crown.

this gave 7.6-1 cr

I would highly recommend using an after market efi system. this will make it far easier to make it run well.

going the carb route is going to cause big headaches.

 

supercharge selection is also important. choose carefully. of course it might all come down to cost.

[averyaaron1979 0]

thanks for all the help from everyone, the project is still in the idea stage and i am still trying to research as much as possible at the moment.

 

the reason i have decided against a mi with a charger was due to all the problems that are likely to be associated with oil surge etc and i don't really want to keep stripping the block and re-building every so often. the other big deciding factor was that i may just run her in the midlands sprint/hillclimb in the near future and going the mi and charging was going to throw me in a high group that i would stand no chance and i haven't checked to ensure that fitting the charger to an 8v won't either.

i was after a reasonable power output but more intersted in the torque, that's why i was looking more into supercharger than turbocharger, unless anyone wants to correct ( as i am no mechanic or even experienced in this field ).

i have no interest in large bhp figures but more torque, the car will never be able to manage more than 120 or much more due to design etc and also british track but i would rather have the low end grunt and pull for the smaller tracks and be able to pull away better than other vehicles.

the carb route was down to an idea that was thrown to me by a friend who builds all manner of daft vehicles and had read of an turbo'd mi on carbs and thought it was an idea that may just work. i am after a system that will be basic and work well and not have many restrictions on ie the original inlet manifold/throttle body etc anc can be tuned to what i am after.

 

my intial plan was a 1900 8v engine

running carbs, unknown if these will be either webers/bikes etc in a sealed intake bo with air intake from the headlight into the charger, directed into a intercooler either infront or behind the raditaor and then directed straight to the sealed carb box. hopefully this shortened distance will reduce boost lag.

as for the inlets for the carbs i have read other threads and came across info that was if i extended the inlet tracts to approx 100mm this would increase torque, would this be the case if increased to 150mm?

unknown cam as i have been advised so far for a catalytic 8v cam or can i go for another cam ie pts torque cam??

is it wise to change the springs for uprated items to cope?

 

 

unfortunately i have no idea when refered to having different pistons under their codes as i have very little peugeot knowledge and i have tried to work which i am after.

can anyone tell me where on the engine the code to work out what base engine i have is?

 

to start to work out all the engine prep work needed is there any bearings etc i need to collect first and start to put together prior to engine re-build.

would it be a wise idea to change the head to an xu10 head or to have the original worked ie ported polished and oversized valves and 3 angle seats? the only reason for that thought was down to the xu9 head being a limiting factor if i remember correctly.

 

the charger i was looking into was a eaton m45 charger off a mini s as proved they fit to the 8v block reasonably easy and are quite readily available. would a i bar boost sound right for my aim or should it be lower than that?

 

would the mi box with a 4.4 final be a worthwhile box to use or should i be looking at a different set up all together? i have no idea on which cluth yet other than it will need to be strong to cope. is there any need to change the gearbox bearing and can this be done easily?

 

although i have started to look into the engine side of things with this project i have got to ensure the rest of the pug is up to and have started tom look into the suspension side of things so far. it will be a 309 beam with 27mm arb and standard torisons, but this may be changed at a later date, with grp a rear mounts.

i was looking into race bushes ( or so called ) for the front wishbone arms , arb etc as it shall run a 309 arb upfront. is there any other suspension upgrades other than coilover s than i need to investigate? can anyone put any ideas experiences forward for this?

 

sorry for all the questions and lack of knowledge but as i said before this is the reasearch time for the project and i would rather use the knowledge that is far greater than mine than just plod on with things and balls things up.

 

thanks again

aaron

[Henry Yorke 269 3 Cars]

I doubt you have the DFZ engine. That will be a 1905cc one but not have the strenthening "spacer" on the sump. Also the ECU will end in 345 and the AFM will end in 207 (IIRC). This engine is only really found in CTI's and 1900 auto 205's which are not common. This has a lazy cam in it and smaller valves than a GTI (DKZ or D6B) engine, however it does lower compresion