New Vixen Project

New Vixen Project

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chris52

Original Poster:

1,560 posts

182 months

Wednesday 18th November 2015
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Moto said:
Hi Chris. Your engine spec sounds like a lot of thought has gone into it. I'd be interested to know a bit more behind why this spec and what you're looking to achieve from it. Also presumably a 711M block or is it an AX? What size valves are they?

Cheers

Moto
The previous owner of the car was going to build it into a track car so purchased a lot of the parts (crank rods pistons head)ready to build a race engine. If I was to start from fresh I don't think I would have gone to this extreme as the costs would have been just to much for a road car. Even having a lot of the expensive parts already I will still end up putting the best part of £3k into the engine and box alone. The block is a late 711M. I did spend a lot of time researching the best way to build this engine and will still be asking a lot more questions as it progresses. The valve sizes are roughly 40mm inlet and 35mm exhaust from memory. I had the block skimmed to give me a deck clearance of 0.005" and with a 0.040" head gasket should give me a compression ratio of about 11.8 to 1, I will set a rev limiter at 8k although this set up will rev quite happily to 9 and beyond. The limiting factors to this set up is going to be the cam as I want a car that will drive reasonably easy. The 244 is on the limit of this as the power band is between 3000 and 8000 rpm but should be ok in a lightweight car.
Chris

Moto

1,230 posts

252 months

Wednesday 18th November 2015
quotequote all
chris52 said:
The previous owner of the car was going to build it into a track car so purchased a lot of the parts (crank rods pistons head)ready to build a race engine. If I was to start from fresh I don't think I would have gone to this extreme as the costs would have been just to much for a road car. Even having a lot of the expensive parts already I will still end up putting the best part of £3k into the engine and box alone. The block is a late 711M. I did spend a lot of time researching the best way to build this engine and will still be asking a lot more questions as it progresses. The valve sizes are roughly 40mm inlet and 35mm exhaust from memory. I had the block skimmed to give me a deck clearance of 0.005" and with a 0.040" head gasket should give me a compression ratio of about 11.8 to 1, I will set a rev limiter at 8k although this set up will rev quite happily to 9 and beyond. The limiting factors to this set up is going to be the cam as I want a car that will drive reasonably easy. The 244 is on the limit of this as the power band is between 3000 and 8000 rpm but should be ok in a lightweight car.
Chris
Ghris

That's got to be the ultimate spec for a fast road crossflow - 8,000 revs eek. I'm no expert but have like wise done quite a bit of research in advance of rebuilding mine and I would like a very similar engine spec. You may need 45 DCOE's though as you'll be pushing it with 40's.

Keep me updated of progress as I'm very interested in your experience of building it and the end result.

Thx Moto

Hullygully

85 posts

213 months

Thursday 19th November 2015
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So...what did you have done to the diff? You say rebuilt...toughened in some way?

chris52

Original Poster:

1,560 posts

182 months

Thursday 19th November 2015
quotequote all
Hullygully said:
So...what did you have done to the diff? You say rebuilt...toughened in some way?
No just rebuilt for now at a local specialist. The diff should be able to cope though as it tends to be torque that kills diff. This engine will have a relatively low torque but high rpm and hopefully somewhere around 150bhp

Grantura MKI

817 posts

157 months

Friday 20th November 2015
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You can run 45s and tune. I like 40s better, but ventures may need to be large. I am sure you will work it out.
Best,
D.

Moto

1,230 posts

252 months

Friday 20th November 2015
quotequote all
Grantura MKI said:
You can run 45s and tune. I like 40s better, but ventures may need to be large. I am sure you will work it out.
Best,
D.
A agree, 40's are better as you'll get more low end torque than with 45's. I run 40's on mine and they are fine but I'm only around 120hp. On paper it may be pushing 40's at 150hp. It'll be interesting to know as at some point I'll aim for 150hp and a new set of carbs will be an expense I'd rather not have.

Andrew Gray

4,969 posts

148 months

Friday 20th November 2015
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Moto said:
Grantura MKI said:
You can run 45s and tune. I like 40s better, but ventures may need to be large. I am sure you will work it out.
Best,
D.
A agree, 40's are better as you'll get more low end torque than with 45's. I run 40's on mine and they are fine but I'm only around 120hp. On paper it may be pushing 40's at 150hp. It'll be interesting to know as at some point I'll aim for 150hp and a new set of carbs will be an expense I'd rather not have.
I run 40s on the Vixen and she is running at 140bhp very well
Andrew

chris52

Original Poster:

1,560 posts

182 months

Sunday 22nd November 2015
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What a wasted weekend. Fitted cam got it all timed up with the vernier gears using a dial gauge. Then dummy built the top end up to find out how close the pistons and valves were ( a cunk of plasticine under the 2 valves) then stripped it back down only to find that the plasticine was hardly quashed. Measured the lift and it was all wrong, eventually pulled the cam only to find out it was a 224 not a 244 as ordered even checked the invoice just in case I had ordered the wrong part but if states 244. So had to strip it all back down remove the cam and will call Burtons in the morning.
lesson learnt check before fitting.

Chris

chris52

Original Poster:

1,560 posts

182 months

Sunday 22nd November 2015
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Dollyman1850 said:
Unless you are circuit racing the car I think you would probably be better off with a 224!
N.
Cheers Neil your probably right but I fancy having a go with the 244 I think it will be ok in this car plus I would like it to be able to cope with the odd track day.
Chris

Edited by chris52 on Wednesday 25th November 21:44

chris52

Original Poster:

1,560 posts

182 months

Sunday 22nd November 2015
quotequote all
The car will be used for the odd track day and blast outs on the country roads. Doubt it will do any more than a 2000 miles a year.
Originally the CR was going to be about 11.8 to 1 but this is just to high and may cause knock issues So I will be aiming for around 11 to 1. This is obviousley static CR the dynamic CR with the kent 244 works out at 8.5 to 1 which should be about perfect.
I was originally going to for the 234 as it would drive a bit smoother with that and was worried that the 244 may be a bit agressive and cause issues with pulling off, but after speaking to a few guys that used them in light weight cars they all said they didn't experience any issues. The carbs I will use I haven't decided on yet but I do have a set of 40'S so will see how they cope.
Chris

Andrew Gray

4,969 posts

148 months

Sunday 22nd November 2015
quotequote all
chris52 said:
The car will be used for the odd track day and blast outs on the country roads. Doubt it will do any more than a 2000 miles a year.
Originally the CR was going to be about 11.8 to 1 but this is just to high and may cause knock issues So I will be aiming for around 11 to 1. This is obviousley static CR the dynamic CR with the kent 244 works out at 8.5 to 1 which should be about perfect.
I was originally going to for the 234 as it would drive a bit smoother with that and was worried that the 244 may be a bit agressive and cause issues with pulling off, but after speaking to a few guys that used them in light weight cars they all said they didn't experience any issues. The carbs I will use I haven't decided on yet but I do have a set of 40'S so will see how they cope.
Chris
Hi Chris the 244 is a good choice I run that in the Vixen
83.271mm bore
77.62mm stroke
1690 cc
plus 0.090" Hepolite pistons lightened and balanced
Crank balanced and ground 20/20
Rods lightened and balanced
Flywheel lightened and balanced
Valve clearances
inlets 22
exhaust 24
Timing 12/13% on tick over and 32% at 3000rpm
That's running twin 40s
Dyno at 132bhp at the last set up after running her in after I did the top end rebuild

As you say not massive Torque but fantastic as a nice fun running car my red line is not as high as your expecting but 6500 and have never taken her much past 5500
At 4500 rpm in fifth she is cruising at 95mph and a real joy to drive so sounds like your heading in the right direction
Andrew


Edited by Andrew Gray on Sunday 22 November 22:21

chris52

Original Poster:

1,560 posts

182 months

Sunday 22nd November 2015
quotequote all
Dollyman1850 said:
Again. you will probably be trying for the biggest chokes possible in a 40 but these also lose flow velocity.

Its your car and your build but if you want to enjoy then I wouldn't be trying to get 8k out of the crank just because you can.
10.5 to 1 max, 234 cam, 7 - 7.5k revs and a longer living engine would be the way I would go..yes you will sacrifice HP.. in a road car though theres not a lot of point having all that power gain so high up in the rev range, unless you plan to scream it everywhere and drive flat out.

My only advice and feel free to ignore it is don't overbuild the engine just because you can.

Race spec crossflows are horrible in road cars.

With CR's be careful with your deck heights…especially if you don't know the history of the engine
N.

Edited by Dollyman1850 on Sunday 22 November 22:21
I appreciate your input but I'm not trying to build race spec engine and you seem to miss understand what I'm trying to achieve here. I said in an earlier post that the main reason I was going this route is because I got a lot of the parts included in the purchase. The last owner was going to build a full race spec engine I am to a certain extent trying to calm it down a bit in order to get more drivability mid range with the option of higher revs without having to worry about cast crank/pistons and rods breaking. I did a lot of research on the best cam for what I wanted and the 244 seemed to fit the bill perfectly. TBH I doubt the car will ever see 8k but its nice to know that it could cope with it if needed. Maybe you will be right and it will be a mare to drive. Time will tel.
Not sure what you mean about deck height on unknown engines? The piston top to deck gap is 0.005" this was my error I got to much skimmed off. I will now have to use a 0.060" head gasket to achieve the 11 to 1 ratio. Agree with you that with a 234 cam should be 10.5 to 1 max as the inlet closes earlier.
cheers for your input
Chris

chris52

Original Poster:

1,560 posts

182 months

Monday 23rd November 2015
quotequote all
Andrew Gray said:
Hi Chris the 244 is a good choice I run that in the Vixen
83.271mm bore
77.62mm stroke
1690 cc
plus 0.090" Hepolite pistons lightened and balanced
Crank balanced and ground 20/20
Rods lightened and balanced
Flywheel lightened and balanced
Valve clearances
inlets 22
exhaust 24
Timing 12/13% on tick over and 32% at 3000rpm
That's running twin 40s
Dyno at 132bhp at the last set up after running her in after I did the top end rebuild

As you say not massive Torque but fantastic as a nice fun running car my red line is not as high as your expecting but 6500 and have never taken her much past 5500
At 4500 rpm in fifth she is cruising at 95mph and a real joy to drive so sounds like your heading in the right direction k
Andrew


Edited by Andrew Gray on Sunday 22 November 22:21
Thanks Andrew that sounds like a very good set up
Chris

anonymous-user

53 months

Wednesday 25th November 2015
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So what happened to the interesting thread. Who requested it was killed off and why?

chris52

Original Poster:

1,560 posts

182 months

Wednesday 25th November 2015
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Some jobs I did before putting it on hold
Restoring the gel coat cracks. this was the most time consuming part of the job and one that I'm glad is all finished now
After Soda Blasting



With the car soda blasted it was difficult to see all the cracks but a great tip from fellow TVR enthusiast on here told me to shine a light behind it to show the defects and it works a treat.



The roof had been damaged at some point and needed major surgery



After a lot of sticky messy work




Chris









Edited by chris52 on Wednesday 25th November 21:44

Grantura MKI

817 posts

157 months

Wednesday 25th November 2015
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Early cars did not use Gel coat. I usually spray the gel coat after sorting the cracks, etc. You can even tint the gel coat to match your paint.
Best,
D.

chris52

Original Poster:

1,560 posts

182 months

Wednesday 25th November 2015
quotequote all
Grantura MKI said:
Early cars did not use Gel coat. I usually spray the gel coat after sorting the cracks, etc. You can even tint the gel coat to match your paint.
Best,
D.
I used to do fibre glass laminating as a job but that was 30 years ago and yes I agree there was no Gel coat as such on the car just a layer of what must have been just resin and then covered in a coat of filler primer. Either that or it was a clear gel coat??
Chris

anonymous-user

53 months

Wednesday 25th November 2015
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TVRMs said:
So what happened to the interesting thread. Who requested it was killed off and why?
It's the PH apocalypse I think
And I thought we were over it by ourselves now anyway?

Dollyman1850

6,316 posts

249 months

Wednesday 25th November 2015
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chris52 said:
I used to do fibre glass laminating as a job but that was 30 years ago and yes I agree there was no Gel coat as such on the car just a layer of what must have been just resin and then covered in a coat of filler primer. Either that or it was a clear gel coat??
Chris
i don't think it is so important to use gel coat with modern hard 2 packs.
My Dads car was on its original paint when I got it, Orange over a grey primer and that was pretty much it.
fibreglass was very much in its infancy back then. a good thick layer of plain resin prior to the layers of matting going on….

N.

Edited by Dollyman1850 on Wednesday 25th November 22:09

chris52

Original Poster:

1,560 posts

182 months

Wednesday 25th November 2015
quotequote all
Dollyman1850 said:
i don't think it is so important to use gel coat with modern hard 2 packs.
My Dads car was on its original paint when I got it, Orange over a grey primer and that was pretty much it.
N.
I tend to agree with you here and didn't even consider applying any gel coat. To be honest I didn't think you could apply gel coat after the fact I thought it needed to be applied to a waxed hard surface and laminated or it wouldn't set properly. But then it was fibre glass baths I used to make and it was a long time ago but would have thought the process was very similar.