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Nomal1st

Engine Swap Vvc Conversion. The Good, The Bad. The Ugly? Where Do I St

12 posts in this topic

Evening fellow Lotuser's.

### The Story ### sleep.png

A few weeks ago my 2000 95K K-Series S1 Elise died of head gasket failure. I stripped it down intending to replace H/G (and all the other gaskets), h/bolts, c/belt + cam seals, w/pump, valve seals, ETC. As such I bought all the above new and spent about £120 in the process.

 

I bought all this as I thought if I'm going to do this, I'm going to do it once and once properly. With this attitude I started getting prices on skimming the head and having it ported, valves re-seated ETC so it was worth putting it back on, there shouldn't have been a warped issue as it never ran over-heated. This all came to a few more hundred and I then started thinking well if I'm going to spend this much I should start looking into better way to spend the money and get more power... after a lot! of Google and head-scratching I decided on a VVC conversion for a cost/BHP+torque gain. Buying a bodywork/chassis knackered VVC MGF was cheaper than a VVC engine on it's own. So here's where I'm at :)

In my Elise at the moment I have a very very clean, perfectly running non VVC 1.8 bottom end and gearbox with 95K miles on it. Next to it I now have a 68K miles VVC complete engine and gearbox covered slightly here and there in oil. I've never heard this engine/gearbox run but been assured it's 100%. The oil is very clean, the gear linkage moves freely and the expansion bottle is spotless. The coolant was beautifully florescent green while pissing out everywhere as I took it out of the MG I bought. The handbrake travels only one click, the wiper washer fluid is blue and the brake pads and discs are in very good condition as it seems this car was very well serviced.

 

###The Question ### mf_eat_arrow.gif
My dilemma is:

1) Do I remove what's left of my Elise engine and replace it for the entire slightly leaky paired VVC engine/gearbox as a one? Meaning the need to hire a hoist and then deliberating whether to strip the head off, change the h/gasket, c/belt, w/pump, seals, sort any leaks... ETC, so pretty much back where I started with additional costs as I believe a lot of the stuff I've already bough isn't useable on the VVC (non VVC head bolts, cam-belt + pulley, h/gasket)

2) Rebuild my current bottom end with the VVC head meaning I can change the H/G and all other bits without effectively adding to my workload (bar the wiring harness!) but ending up with a bottom end and gearbox carrying 95K miles instead of 68K.

 

Is there any advantage to keeping the VVC bottom end and gearbox matched with the VVC head? Is the MGF VVC PG1 gearbox the same ratio's as the Elise 1.8 non VVC?

Any thoughts appreciated mf_frankie.gif

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First question, is it a EU 2 VVC engine ( MGF ) or a EU3 ( MGTF ) VVC engine?

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Good shout, it's the EU2 143 BHP MGF VVC 18K89 I believe off the top of my head.
My current Elise engine is the standard 1.8 K-Series and I'm also certain it's on the original head gasket at 95K so clearly been well cared for. I've had my Elise almost six years exactly and done nearly 40K of the 95. When cold my original PG1 gearbox can be awkward.

 

Cheers.

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Dont know much about the S1 but does that have shorter ratios like the S2 VVC? On an S2 I'd go with cams and head work over VVC and you're keeping a whole level of complexity out of the engine.

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The MGF VVC has a closer gearbox (3 and 4 are the same output as S1 111s). Regarding the Engine choice: what do you want to do?

 

a VVC conversion? you will have to update all harness etc...

 

A VVC Solid cam conversion? you will need banking pate and a set of piper 270 if you remain with the original ECU.

 

In mine, I have a C4BP gear box, a std bottom end and a solid camed vvc head. This is basically a MGF powertrain with cam and original elise S1 harness. It is possibly one of the simplest conversion and allows for further development such as piston update, cam update...

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Fentuz your conversion sounds good for those on a budget. Is your vvc head standard? What sort of power will a standard vvc head and piper 270 solid (i.e non-vvc) cams give?

Presumably it will run on the s2 engine management?

 

Sorry to bombard you with questions!

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Yes, it is a standard head. Depending of cam timing etc.. you basically get the same figure as a S1 111S

In my case, I get just above 130lb.ft from 3.5 to 6.0 krpm but I run Emerald and ancillaries. It is recommended to up the fuel pressure a little, toward top of the spec i.e. 3.2 Bar BUT it may be more depending of the AFR. In my case everything was set to run 12.5/12.6 AFR across the range.

On a S2, I think it would be good to run S1 injector and with a bit of luck, it will give you the correct AFR.

 

I know people who run 633 and they get very near 160 bhp with emerald.

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Come again?!?

 

So you are looking at about 143bhp then?

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Dont know much about the S1 but does that have shorter ratios like the S2 VVC? On an S2 I'd go with cams and head work over VVC and you're keeping a whole level of complexity out of the engine.

Thanks for the input Jonnyboy. I looked into this heavily when I was originally looking into just replacing the head gasket on K-Series S1. I thought I'd best have the head skimmed at the same time then started getting deeper, considering porting, flowing, polishing, valves regrinded or increased... ETC. Spoke to DVA and other and I ended up with well over £1K's worth of work and a long waiting list. This was only going to achieve about 150 BHP and pretty much take my standard head to it's BHP limits on air flow. So then started considering the VVC conversion and as a competent mechanic and electrician it's something I could do at home for less than £500 and easily get the same amount of horses with a much better torque curve than head work to a standard head AND being the VVC head I'm left with much more avenues to go down later if I seek more power. So I'll be sticking with this route for now I think as it offers me a lot more cheers.

 

The MGF VVC has a closer gearbox (3 and 4 are the same output as S1 111s). Regarding the Engine choice: what do you want to do?

 

a VVC conversion? you will have to update all harness etc...

 

A VVC Solid cam conversion? you will need banking pate and a set of piper 270 if you remain with the original ECU.

 

In mine, I have a C4BP gear box, a std bottom end and a solid camed vvc head. This is basically a MGF powertrain with cam and original elise S1 harness. It is possibly one of the simplest conversion and allows for further development such as piston update, cam update...

It will be a straight VVC swap with the standard cams for now Fentuz. In the future I may blank them off but need to get it back on the road for now so wondering weather to rebuild my current bottom end or chuck the whole VVC unit in as it is to then only worry about the head gasket in that, but at the same time, if it aint broke don't fix it! Also now I'm wondering what gearbox to stick with and thinking probably the C6BP as sadly I drive more than I thrash :L

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yes, 143 to 155 depending of ancillaries and timing

 

You might get more with an EU3 VVC head as the inlet and exhaust valves are unshrouded a bit on this head.

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After swapping a standard 1.8 k-series to a 143bhp VVC in an S1 I noticed a definite increase in power at the top end which felt great as it normal feels like it runs out of puff further up the rev range, BUT I also noticed a lose of low down torque, which to me was a real negative and something that had I known about may have put me off.

 

If I was doing it again I'd go for a VVC head but blank off the vvc and fit some wild cams etc - simialr to Bill's (Fentuz) Elise, his engine pulls very well!

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