Converting Dfw To D6c

[pete1986 2]

Ok, in the very near future i am looking to get an inlet cam from Peter T. My mi16 is a dfw and to run a stage 2 inlet cam he recommends at least 10.1 CR, mine only has 9.7. So i want get the cr up and get a stage 2, providing its not just a waste of time and money, and i would be better off just going for a stage 1. As i understand it, the differences between dfw/d6c are the inlet cam pulley (mine has been changed to a d6c #4), pistons and the ecu. A mate of mine has a spare set of d6c pistons ready to go in, but i was thinking that it would be easier to just change the blocks over, would that work or would the dfw ecu be a problem with the extra sensors?? How far behind the d6c, in terms of power, would it be with this sorted, would the dfw ecu still be holding it back from reaching the magic 160hp??

 

Im also thinking of getting one of Peter T's chips aswell (anyone had experience of these?), but aside from this what else could i do to get a bit more power without going down the twin carb/TBs road and spending silly money?? I suppose if the head is coming off to swap the pistons/block, i could get it skimmed. Do mi's respond well to this??

 

Thanks in advance,

Pete

[pp205 17]

Hi Pete,

 

I have just got my DFW Mi back up and running following bottom end failure. Whilst the head was off I had 1.4mm skimmed off of the block and liners after consulting with PeterT, this raises the compression ratio up to 10.8:1.

 

Having done about 100 miles since the rebuild it feels really nice and smooth and although I haven't taken it to the limit yet (need to do a few more miles to run it in again) it feels like it wants to pull like a train!! I can definately notice the difference from before the block skim, hope that helps,

 

Simon

[cybernck 400 1 Cars]

well, a couple of nights ago i drove friend's 405 Mi16 with a rebuilt DFW engine,

petert's inlet cam (not sure which stage though) and petert's chip (along with

some other mods, such as a thin copper headgasket and a XM throttle body)

and i must say i was very pleasantly surprised as the engine felt very revvy

and responsive and kept pulling strong to 7000 rpm (didn't dare to take it higher)

therefore i can wholeheartedly recommend it .

[petert 551]

I recommend skimming the deck/liners whether you have a DFW or D6C. Obviously different amounts have to come off each to obtain zero deck height. The combined result of decreasing the squish distance and increasing the CR to 10.8:1 makes for a very pleasant engine. Nice and crisp.

 

Skimming the head doesn't really achieve much, other than dressing the surface to improve sealing ability.

[pete1986 2]

Thanks fot your comments everyone, mucho gracius!!

 

After consulting Peter T, QEP and a little of my own research, i think its best to do the following;

 

Swap to D6C block

Deck the block/liners

Relap the valves and sort any other apparant head issues

Stage 2 inlet cam

Chip

4-2-1 manifold

 

Can anyone add anything else to that list that would be worthwhile doing when the engine comes out?

 

Peter T- How much should the D6C block/liners be decked by?

 

The email i got back from QEP (think it was markus) said that even after much time spent on the flowbench, there is very little that can be done to improve the mi16 head. I knew that the standard head flowed well as standard but i thought there was room for improvement, considering quite a few people on here have ported and polished heads in their signature.

[petert 551]

Peter T- How much should the D6C block/liners be decked by?

 

You'd normally do a trial assembly and measure how much needs to come off. However, if you're going for a "stab in dark", I'd take 0.35mm. Theoretical D6C compression height is 37.10mm. Deck height is 37.50mm. So taking 0.35mm off will leave 0.05mm, theoretically.

 

Also keep in mind that you'll need to verify the valve to piston distance if you're using my Stage II grind. You may need to cut the inlet pockets a tad deeper (say 0.25-0.5mm).

[pete1986 2]

Great thanks Peter, as helpfull as ever!

 

So the only DFW part left would be the ecu. How much will this be holding it back? Theres a distinct 'boost' at 4000rpm with DFW's, is this because of the ecu or will the cam and chip cure it and give a more steady power curve? ie. more power below 4000rpm

[petert 551]

So the only DFW part left would be the ecu. How much will this be holding it back? Theres a distinct 'boost' at 4000rpm with DFW's, is this because of the ecu or will the cam and chip cure it and give a more steady power curve? ie. more power below 4000rpm

 

The boost you feel at 4000 is because of the lack of torque below 4000. The D6C has a flatter torque curve, so thus more linear in acceleration. The DFW chip is OK, much better than any 2 row, but not as good as one of mine.

[Sejo 0]

well, a couple of nights ago i drove friend's 405 Mi16 with a rebuilt DFW engine,

petert's inlet cam (not sure which stage though) and petert's chip (along with

some other mods, such as a thin copper headgasket and a XM throttle body)

and i must say i was very pleasantly surprised as the engine felt very revvy

and responsive and kept pulling strong to 7000 rpm (didn't dare to take it higher)

therefore i can wholeheartedly recommend it .

 

I´m proud to own the Mi16 cybernck is talking about

 

Mods done to the engine as above, with peter`t-s STAGE I inlet cam. I`m more than satisfied with the power I have now.

Cybernck-s words describes it as it is and I think this guy knows what is he talking about after having experience with cars like 205 Mi32 and 405 T16

[pete1986 2]

^^ That 405 looks pretty slick ^^

 

well, a couple of nights ago i drove friend's 405 Mi16 with a rebuilt DFW engine,

petert's inlet cam (not sure which stage though) and petert's chip (along with

some other mods, such as a thin copper headgasket and a XM throttle body)

and i must say i was very pleasantly surprised as the engine felt very revvy

and responsive and kept pulling strong to 7000 rpm (didn't dare to take it higher)

therefore i can wholeheartedly recommend it .

 

So whats the benifit of a citroen xm throttle body?

[Sejo 0]

^^ That 405 looks pretty slick ^^

 

 

 

So whats the benifit of a citroen xm throttle body?

 

 

XM TB is bigger. you get approx 25% more air for the engine.

[pete1986 2]

XM TB is bigger. you get approx 25% more air for the engine.

 

Another thing to add to the list.

 

I went into QEP the other day and talked to Marcus about the work. They suggested just relapping the valves, re-cutting the seats and a quick skim and wash for the head. But he also said (after consulting matt) that decking the block would be a waste of £250. I was quite surprised at this because Peter T had recomended it, and also another forum member said it made a noticable difference to his (2nd post of this topic).

 

Marcus also commented that i was being brave using a reground cam. Has any one ever had bad experiences of regrinds in an Mi16?

[welshpug 1,622]

surely if you just run D6C pistons in a DFW you'll get D6C compression and save the need for all the machining work?

 

stick in a thinner gasket and a head skim if you feel its absolutely necessary to raise the compression further without spending money on new pistons.

 

but new higher compression pistons wouldn't be that far off the price of the machining work to the block and liners and allows an even higher compression ratio.

 

 

genuinely interested inthis, as I do want to build a sort of special build one day not just stock rebuilds

[pete1986 2]

surely if you just run D6C pistons in a DFW you'll get D6C compression and save the need for all the machining work?

 

Yeah thats true, but the idea is to deck a D6C block and achieve 10.8 CR. But if Matt thinks it isnt worth it then im not going to bother.

 

When you say fit a thinner gasket, welshpug, do you mean the copper ones? I read about these but the idea of replacing them every 2-3 years doesnt appeal

 

So has anyone had any problems with reground cams in an mi?

[maxi 36 1 Cars]

Yeah thats true, but the idea is to deck a D6C block and achieve 10.8 CR. But if Matt thinks it isnt worth it then im not going to bother.

 

When you say fit a thinner gasket, welshpug, do you mean the copper ones? I read about these but the idea of replacing them every 2-3 years doesnt appeal

 

So has anyone had any problems with reground cams in an mi?

 

 

First of all, just a suggestion but why not sell your DFW and stick a D6c in there to begin with???? Im sure I have a couple of 160bhp looms kicking about with ecu etc. Would save a lot of f***ing about, time and money which will only get you up to a std D6C anyway.

 

Stay away from reground cams, when the base circle has material taken from it the cams lose their hardening and eventually the whole lobe wears away. The fast road regrinds I had ended up with less lift than std in the end.

 

Maxi

[pete1986 2]

Cheers for the heads up about the cams, just drove past you about half an hour ago maxi.

 

I would essentially have a d6c engine by sticking a d6c block on. A mate of mine has a spare block in very good condition. Dan sorted the cam timing when he did the conversion last year with a #4 pulley. So the only thing 'dfw' left would be the loom and ecu. Question is, how much would this be holding it back? standard/with a peter t chip??

 

How much of a mission is it to swap the loom over?

[petert 551]

Stay away from reground cams, when the base circle has material taken from it the cams lose their hardening and eventually the whole lobe wears away. The fast road regrinds I had ended up with less lift than std in the end.

 

That's a big call Maxi. There's nothing wrong with a reground provided your know the limits of what you're trying to achieve. I'd much rather sell a new billet cam for $375 than a reground for $185. But the reality is at entry level, the Stage I reground cam with 0.350" lift will equal that of a new billet with 0.400" lift. The lift is simply not the limiting factor at 220-230 deg. duration (@0.050") in an Mi16.

 

As for hardening, Mi16 cams are factory hardened to a depth of approx. 4-5mm. So taking 1mm off the base circle is very safe. Lobes only wear away from incorrect running in procedures.ie incorrect oil (no zinc), old lifters on new lobes, insufficient break in period. This happens less so on Mi16 cams which are very hard, but a lot on the softer 8V cams.

[maxi 36 1 Cars]

That's a big call Maxi. There's nothing wrong with a reground provided your know the limits of what you're trying to achieve. I'd much rather sell a new billet cam for $375 than a reground for $185. But the reality is at entry level, the Stage I reground cam with 0.350" lift will equal that of a new billet with 0.400" lift. The lift is simply not the limiting factor at 220-230 deg. duration (@0.050") in an Mi16.

 

As for hardening, Mi16 cams are factory hardened to a depth of approx. 4-5mm. So taking 1mm off the base circle is very safe. Lobes only wear away from incorrect running in procedures.ie incorrect oil (no zinc), old lifters on new lobes, insufficient break in period. This happens less so on Mi16 cams which are very hard, but a lot on the softer 8V cams.

 

 

 

Fair point Peter. With the information posted above I stand corrected. Just posting my findings and what I was told by an engineer.

 

Maxi

[Francesco 2 1 Cars]

Interesting reading, as I have also a DFW. For the XM TB, from wich XM engine?