Autobahn Thrash

All chat, general/off topic/banterish and questions relating to the BX16valve.
Jack
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Autobahn Thrash

Post by Jack »

My late 16v Cat BX which has the DFW engine which is best for supercharging. The car currently goes but is an MOT failure because of emissions... It also has cosmetic rather than structural bodywork damage to the offside rear quarter.

So I am wondering what top speed and reliability could be obtained from this engine if it was properly researched and supercharged, and let’s say installed in an earlier BX that doesn’t require a cat. (I have another one like that with an MOT). I am just wondering how much power could be obtained from this engine without sacrificing reliability and what top speed might be expected on an autobahn.
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jayw
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Post by jayw »

I would have liked to have made that a reality, but unfortunately that all fell through...
Now listen here you mullet...
Jack
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Post by Jack »

well actually i was thinking more of a group project.... but first I think we need to know what might be achieved
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Post by Vanny »

I reckon this thread might be a good start;

http://bx16valve.co.uk/forum/viewtopic.php?t=1819


Did you sell any of those cars in the end? I sent various people in your direction (through the forum) but they never seemed to get anywhere.
Jack
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Post by Jack »

Hi Vanny, thanks for the link. Yes despite your good efforts I’ve still got all the cars. I had a couple of enquiries, (much appreciated , thank you) both for the red Phase 2, but not even the serious one worked out.

Well my little publicise-the-BX idea needs 150mph, and it seems the six-speed gearbox/cutout is a bigger problem than power. Current non-technical options are:
1) if Rotrex works on the standard engine, modify a standard 160 bhp engine on a non-cat car
2) modify the low compression engine and leave it in the Ph 2 car with the cat
3) modify the low compression engine and fit in the Ph 1 - no cat (probably the one that Jon did all the welding on, which might be reassuring at 150mph).
would all those options reach 150mph with a six-speed box? If option 3 is best, any idea how much better it would be (top speed / reliablility)? Should any option be eliminated and not considered?
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docchevron1472
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Post by docchevron1472 »

erm, with solid tappets and a broken speed limiter a standard valver will do 150 as is...
1990 BX 16v Phase 2
1989 BX TD hybrid
1971 BL 350FG Ambulance (unique)
1993 Dennis Lance 132
That's when I reach for my Revolver
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jayw
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Post by jayw »

At this point it is very worth considering the complete Rotrex conversion will cost upwards of £4000.

And also just to point out, I would have had the car no problem but was told it HAD to be gone that weekend and when plans got changed was given just one day to find a trailer...

I'd still have had the car now but it seems my plans for the engine have been hijacked.
Now listen here you mullet...
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Simran
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Post by Simran »

Doc, what do you mean by 'broken speed limiter' ?

The bx will never do 150 on the standard engine, solid tappets alone wont allow it to rev any higher as the rods will also limit that and the engine isnt making enough power higher than the factory rev limit to make it to 150. My car would max out at around 130-135 and it wasnt on the rev limit in top so raising the rev limit if thats what you mean wont allow you to go any faster.

An extra 15 or so miles an hour will require a considerable amount of power or loss of weight to achieve i reckon.

Jack, to make the most of your engine naturally aspirated, you will need the D6C pistons to raise the compression cheaply. If you go second hand, this is the cheapest option but beware of knackered stuff and fit new rings. Brand new pistons from a good company are around the same price as a second hand supercharger from ebay (£500 ish) which would work on your low compression engine. Close to 200bhp naturally aspirated will get you around 150mph, maybe even a bit faster but will cost you almost the same as a diy supercharger conversion and the supercharger will give you the potential to make alot more power without as much expenditure as NA.

to get 200 bhp NA you will need lairy cams (£500 ish), £500-£1000 worth of head work (porting, bigger valves and 3 angle valve seats) , Long exhaust manifold (£500) and maybe throttle bodies and a new programmable ecu to get the fuelling right plus bigger injectors.

To get 200bhp with a supercharger, you can pretty much do away with the head work, cams, exhaust manifold and throttle bodies. Ive seen people run superchargers with standard ecus, all theyve done to get around teh fuelling issue is double the fuel pressure and it works well enough to provide the extra fuel plus a bit to prevent detonation. Plumb in an Air:fuel ratio guage and an adjustable pressure regulator and monitor air:fuel ratios. If theyre too lean, richen it up a bit with more pressure, too rich then drop the pressure a bit. Superchargers are pretty linear in power delivery compared to turbos so you can get away with such a simple bodge to get you by.
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Simran
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Post by Simran »

If you go the supercharger route and would rather use a programmable ecu, i cant recommend a megasquirt enough. Damn cheap and has a built in data logging feature so it makes it so much easier for other people to help you out because they dont actually have to be with you and the car to analyse your maps and settings, you can just email them to someone to have a look over and adjust. I reckon that route would still work out cheapest.
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docchevron1472
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Post by docchevron1472 »

Simran wrote:Doc, what do you mean by 'broken speed limiter' ?

The bx will never do 150 on the standard engine, solid tappets alone wont allow it to rev any higher as the rods will also limit that and the engine isnt making enough power higher than the factory rev limit to make it to 150. My car would max out at around 130-135 and it wasnt on the rev limit in top so raising the rev limit if thats what you mean wont allow you to go any faster.
Largely I meant remove the rev limiter.
True, the engine would most likely only do it once before exploding but meh..
As it goes I have a 2 row ECU that went entirely nuts. The rev limiter went ape, as in, I went well past 8K and no doubt it would have kept going til it blew.
Ok, this is a fairly fresh engine, but I had a sat nav approved 142mph and I have no doubt at all it would have kept going had I not pulled the plug since I have no wish to build yet another D6C lump.
AS is, with shiny replacement ECU my engine will happily bounce off the rev limiter all day, and thats a stock engine, no forged pistons, no supercharger or any bolt on crap, the only mild divergance is a slightly larger TB..
1990 BX 16v Phase 2
1989 BX TD hybrid
1971 BL 350FG Ambulance (unique)
1993 Dennis Lance 132
That's when I reach for my Revolver
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Simran
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Post by Simran »

In all fairness the only three 16v's ive been in have been fairly well used, so maybe a fresh one manages to reach the limiter in 5th. I wouldnt like to spend too long past 7200 though, our 206 at uni with a gti6 engine broke its standard rods when they were put back in to replace the fancy rods that were in it for racing, when asked to go beyound their limits.
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Kitch
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Post by Kitch »

Simran wrote:Doc, what do you mean by 'broken speed limiter' ?

The bx will never do 150 on the standard engine, solid tappets alone wont allow it to rev any higher as the rods will also limit that and the engine isnt making enough power higher than the factory rev limit to make it to 150. My car would max out at around 130-135 and it wasnt on the rev limit in top so raising the rev limit if thats what you mean wont allow you to go any faster.
I dunno, mine hit the limiter in 5th just after I got it which I'm told equates to 143mph with standard wheel, gearing etc. Mine is quite cammy; all it's power is after 5k revs. Before that it's dead, more so than other valvers I've driven.

Now it's been chipped up, the rev limiter is set to 7800rpm. Now its not worth revving it past 7500rpm to be honest as it tails off power sharply afterwards, but I think the extra 300rpm to 7500rpm would probably give a few more MPH.

However.....since it was chipped it's alot more gutless at the top end (all the advantages come in 2nd and 3rd gear) so as it stands, it still wouldn't do it!
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jayw
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Post by jayw »

In response to the "standard" speed acheivable, I also had a sat-nav confirmed 142mph almost at the limiter with a completely stock setup and RR'ed @ 150bhp. In fact, my Youtube vid some will have seen saw 134mph in less than a mile once in top.

With the ratios in the standard gearbox, 5th gives you 20mph per 1k an as such a theoretical top speed of 144mph at the limiter. With the TD 5th cog that increases to 22mph per 1k.

So, if you can restore the 160bhp that almost all our (unmodified) cars inevitably now lack then 150mph is achievable with little more than a cog change or the raising of the limiter to 7.6k and a very very long stretch of favorable road...
Now listen here you mullet...
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jayw
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Re: Autobahn Thrash

Post by jayw »

Jack wrote:My late 16v Cat BX which has the DFW engine which is best for supercharging. The car currently goes but is an MOT failure because of emissions... It also has cosmetic rather than structural bodywork damage to the offside rear quarter.

So I am wondering what top speed and reliability could be obtained from this engine if it was properly researched and supercharged, and let’s say installed in an earlier BX that doesn’t require a cat. (I have another one like that with an MOT). I am just wondering how much power could be obtained from this engine without sacrificing reliability and what top speed might be expected on an autobahn.
Also worth considering this motor may well be failing emissions because it's Rubber-Ducked! Either way, a minimum of £350 basic rebuild is gonna be required before you so much wave a supercharger anywhere near it
Now listen here you mullet...
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docchevron1472
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Post by docchevron1472 »

I had mine dyno'd (albe it a long time ago now) and it turned 172BHP.
I'm not altogether sure the machine was entirely accurate as I cannot believe it was capable in stock form of anywhere near that, but the bloke was insistant it was right..


Anyway, goign back to topic a tad..

I'd say a £350 basic rebuild wouldn't be anywhere near enough to get the reliability with the power and speed desired here really.
If reliability is all important then you're really looking at a full, careful, rebuild done by someone that knows all about these engines and not just "jock down the back road garage"..
It'll cost a lot of money.
Then there's the transmission to consider. It'll have a few miles on it already, is it really good enough? and so on and so on ad nauseam..

Personally, I like the valver as it is.
Ok, if you want to build a track car and use it in anger, then fair play, but for daily living it's grunty enough as is IMHO.
1990 BX 16v Phase 2
1989 BX TD hybrid
1971 BL 350FG Ambulance (unique)
1993 Dennis Lance 132
That's when I reach for my Revolver
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