The V8 Owners Forum -

Hi,

My head is spinning from all the reading I've been doing so wondered if those who have played with a few options could give their opinions.

I'm intending to put a 3.9/4.0 into a Sportscar and I'm looking for around 240bhp with something like a 275 cam and mild porting etc.

I think the main options are:

Hotwire (crude, simple, cheap, easy to fit)
GEMS (better but harder to get working out of a Rover)
Thor (as above)
Weber 500 (simple but effective, although will it cost me power and mpg)
Megasquirt (I don't like the idea of paying someone to map something once when with this I can tinker after every mod I make, unless I'm adding complexity for minimal gain)

At the relatively low power level would I miss out on much by running the Hotwire ?

From what I can see this is the simplest and cheapest option.

If I run a 275 cam presumably I'd need a remap on any of the std systems - what would this cost ?

I've played with aftermarket ECU's before (though not the MSquirt) do I need this level of complication though ?

This is hopefully a cheap project at £3500 all in for the entire transplant and I cover maybe 5k a yr in this car so there's not much point paying £500 for an extra 2mpg or 5bhp.

Your views please.

What is the situation with SVA / IVA testing? You might be forced into using GEMS / Thor anyway.

I personally would advocate a 4.6 with GEMS or Thor, getting a standalone ECU (defender 50th anniversary style) from Mark Adams.

Chris.

Hi,

No probs with any tests or MOT etc

4.6 adds cost and for my relatively low power requirement I felt the shorter stroke would also be beneficial.

How much does the Mark Adams solution cost - I can't seem to find his website.

Oh I'd be mating it to a 5 speed so I know that means I'd need a crank mounted trigger but it seems to be widely available.

Having seen that he charges almost £800 for a chip upgrade on Ebay I don't think we are on the same wavelength, I know he is very good but I can't justify that kind of price.

At that price I'd be going with a Megasquirt so I get a cutom tune rather than a generic one.

Cheapest route would probably be hotwire - scavanged from a rangie or the like Yes after market chipping is pricy.

Personally on a budget though I would stick on a Weber 500

As you say will you notice the last 2 mpg and or 5 hp - unless you on an economy rally or a track racer probably neither apply.

Ian

Thanks but I guess what I meant was that I'm not bothered about the last bit of performance / economy but what are the likely performance / econmy differences between the options ?

For example I'm told the Weber is very good and set up right would give better performance and similar economy than the std (pre GEMS) injection - is this true ?

Have you thought about sourcing a 4 litre from a Scrapped TVR Chimaera.

500 carb properly set up wont hinder you in either performance or fuel economy specially at the levels your looking at. However I think that 240 honest bhp with the spec you are on about is reaching a bit. I think you need more cam or better yet better than mild porting on the heads.

ged wrote:Have you thought about sourcing a 4 litre from a Scrapped TVR Chimaera.

I have but I have yet to see any nearby plus they seem to fetch quite a premium and no one seems to be able to tell me what they had done to get the power.

It seems to me they just fitted a cam, larger trumpets and a better ecu in most cases.

Plus my old Griff 500 needed a chip to make it run correctly so it would seem an expensive option really.

katanaman wrote:500 carb properly set up wont hinder you in either performance or fuel economy specially at the levels your looking at. However I think that 240 honest bhp with the spec you are on about is reaching a bit. I think you need more cam or better yet better than mild porting on the heads.

Thanks.

You may be be right as its surprisingly hard to find good dyno results IME.

The weber 500 may well produce the results indicated above - BUT you will need to have the patience to tune it. Which will involve getting a jetting kit and a wideband lambda setup. They are in my opinion reasonably easy to jet compared to a holley - as needle and jet changes can be done from the top of the carb.

The problem is that once you get a wideband you will realise how poor carbs are and you will want to go EFI (well that's what happened to me anyway!)

I think you're right (I have mapped my current car) but this project was supposed to be simpler !

I've spent many hours reading your site which is excellent - cheers.

But the more I read the more I'm tempted to spend.

Been reading a lot about the Megasquirt and having seen the frankly ridiculous cost of chipping a V8 (compared to most other cars) it seems a no brainer that if I go injection, I'd go with a Squirt too.

Mark adams charges far too much for his chips. If they were more like £300 i would of got one of his chips for my P38 Gems, which would of benefited from it.
Spending £800 for a chip on a £2k P38 4.6 is a joke - mark needs to realise that the cars are worthless now. He could probably make more money by reducing the cost of the chips to capture this lower end of the market now.

Agree with that. It would also open up his market hugely to people buggering about like us lot!

Chris.

Some manufacturers realiose this and have reduced parts and labour on some older cars.

In fact the Chip for my wife's Volvo was reduced as its over 5 yrs old.

Better to have a bit of something than all of nothing.