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Author: Subject: Struggling to put the power down, bigger tyres?
Nickp

posted on 22/9/17 at 08:17 PM Reply With Quote
Struggling to put the power down, bigger tyres?

Just had another great day at Blyton, but car would've been so much quicker if I could get on the power sooner out of the corners. The back end was wanting to step out all the time, which can be fun but not the quickest way round.
The front feels great and I'm currently at 400lb/300lb F/R spring rates. The rear GAZ shocks have been rebuilt but tbh their adjustability seems pants to me, going from no damping to too much damping (slow return after compression) in one click. If I go anything above a couple of clicks from full soft the problem gets worse. Ultimately I'll be swapping these out for a full set of Protech ones when funds allow but the question is, am I asking too much of a 205/50/15 road / track tyre (AD08R) to put down 230bhp?
The car was always going to be a bit of a beast and will be getting a 3.0 260bhp upgrade in the future, so should I maybe be looking at 225/50/15 rears?

BTW I tried to keep the tyres in the 18-20psi range.

https://www.flickr.com/photos/frankhall/albums/72157686207215311

[Edited on 22/9/17 by Nickp]

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CosKev3

posted on 22/9/17 at 10:11 PM Reply With Quote
205 should put down 230bhp once you get them warm I would think with semi-slicks.

Have you got adjustable rear geometry? If so has it been set up?

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Nickp

posted on 23/9/17 at 04:28 AM Reply With Quote
quote:
Originally posted by CosKev3
205 should put down 230bhp once you get them warm I would think with semi-slicks.

Have you got adjustable rear geometry? If so has it been set up?


Thanks for the reply. Yeah, rear camber is set at 1.5neg and zero toe IIRC.
Car has a near perfect 50/50 F/R weight distribution (unladen) so I think it should be able to be made to handle better than it currently does.
The thing with this engine is it makes 210lb-ft @3950 compared to a Hayabusas 98lb-ft @7000. I don't think anyone would consider a Hayabusa engined 7 slow or gutless but this thing is a different proposition

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jeffw

posted on 23/9/17 at 06:26 AM Reply With Quote
And the Busa engined version would be lighter by over a 100Kg (and probable a lot more)...

Anyway, the most important item in getting you out of corners (apart from tyres) you've not mentioned, so what type of LSD do you have?






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peter030371

posted on 23/9/17 at 06:56 AM Reply With Quote
How much do you use your car on the road in the wet? Rather than bigger tyres I would fit more track orientated tyres such as Toyo 888 or A048 ( and assume you have a decent diff with that much power in a 7)
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matt5964

posted on 23/9/17 at 07:11 AM Reply With Quote
We have just under your figures and currently run toyo R1Rs and donít get issues with putting the power down in the dry, wet is a different story.. both on track and road. Will be getting some R888Rs or A048s next year for track

18psi all round.

I would get the geo checked.

Have you got a reasonable throw on the loud pedal?





Luego velocity XT 2.0ltr 221.3bhp 178.9lbft

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Nickp

posted on 23/9/17 at 07:11 AM Reply With Quote
quote:
Originally posted by jeffw
And the Busa engined version would be lighter by over a 100Kg (and probable a lot more)...

Anyway, the most important item in getting you out of corners (apart from tyres) you've not mentioned, so what type of LSD do you have?


Mine's 630kg so yeah a BEC could easily be 100kg less.
Just a bog stock Sierra LSD, unfortunately

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Nickp

posted on 23/9/17 at 07:21 AM Reply With Quote
quote:
Originally posted by matt5964
We have just under your figures and currently run toyo R1Rs and donít get issues with putting the power down in the dry, wet is a different story.. both on track and road. Will be getting some R888Rs or A048s next year for track

18psi all round.

I would get the geo checked.

Have you got a reasonable throw on the loud pedal?


I will recheck the geo myself. I have a digital inclinometer (camber gauge), tracking gauge and string
What rear camber / toe do you run?
Yeah, the accelerator has good travel, certainly not on or off like some BECs can be.
I think I need to look at my spring rates (as well as the rear shocks). My previous track day, on road tyres, I was running 400/200lb springs. Rear was far too soft and bottomed out everywhere but the car actually felt better balanced. Maybe this was a step too far to 300lb? I could go a bit softer on the rear or maybe a touch harder on the front to restore the balance and reduce roll too?

[Edited on 23/9/17 by Nickp]

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Camber Dave

posted on 23/9/17 at 07:58 AM Reply With Quote
Have you checked the tyre temperatures?
They will dictate the correct camber.

Also have the tyres worn evenly right accross the width?
If not you may need a front antiroll bar
It will increase the weight transfer at the front and make the rear more compliant.

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Nickp

posted on 23/9/17 at 08:06 AM Reply With Quote
quote:
Originally posted by Camber Dave
Have you checked the tyre temperatures?
They will dictate the correct camber.

Also have the tyres worn evenly right accross the width?
If not you may need a front antiroll bar
It will increase the weight transfer at the front and make the rear more compliant.


No I didn't measure tyre temps but will get something to do this in future.
The tyres do seem to be wearing evenly tbh.
A front ARB is something worth considering, especially if I could make it adjustable.

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sdh2903

posted on 23/9/17 at 08:28 AM Reply With Quote
I'd say your rear springs are too firm. My last westy was a similar ish weight to yours and i ended up on 225lb rear springs and I'm heavy too.

It had 250bhp and 300ftlb of torque. R888r in 205 width could just cope with getting the power down but only once warmed up. Struggled to keep heat in them on the road and they weren't good in the wet so swapped to R1R. To be honest the R1r were hopeless in the dry I could easily spin up through 3rd into 4th. They were however better in the wet. I had r1r on my last BEC and they were fantastic but couldn't cope with the torque of the ecoboost.

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procomp

posted on 23/9/17 at 08:32 AM Reply With Quote
Hi. You identified the problem when you said the dampers have no real adjustability.
In simple terms you cant expect to put the power down if you have no control of the basic weight transfer. Adding ARB,s is pointless untill the basics are sorted as they are used to fine tune balance not cure the fact that the dampers have no control.

Cheers Matt

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Nickp

posted on 23/9/17 at 08:51 AM Reply With Quote
quote:
Originally posted by procomp
Hi. You identified the problem when you said the dampers have no real adjustability.
In simple terms you cant expect to put the power down if you have no control of the basic weight transfer. Adding ARB,s is pointless untill the basics are sorted as they are used to fine tune balance not cure the fact that the dampers have no control.

Cheers Matt


Matt,
I'll be calling you in a bit if that's ok?

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procomp

posted on 23/9/17 at 08:59 AM Reply With Quote
Ill u2u mob as im off to Snetterton shortly.
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Neville Jones

posted on 23/9/17 at 11:56 AM Reply With Quote
As a couple have said, rear springs appear to be way too stiff, 225 would be too high, and from what I',ve experienced, I'd go 175. But, the numbers need to be done to get the right springs front and back.

Shocks not working properly will not be helping either.

Cheers,
Nev.

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Nickp

posted on 23/9/17 at 02:08 PM Reply With Quote
quote:
Originally posted by Neville Jones
As a couple have said, rear springs appear to be way too stiff, 225 would be too high, and from what I',ve experienced, I'd go 175. But, the numbers need to be done to get the right springs front and back.

Shocks not working properly will not be helping either.

Cheers,
Nev.


I've already had 200lb springs on the back (bought in error) and they were too soft. The Haynes book advises 350 FR 250 Rr, I'm currently 50lb up on these, but maybe need to go back to 250lb or 275lb.

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jeffw

posted on 23/9/17 at 04:03 PM Reply With Quote
Spring rates will not matter that much if you are running rubbish dampers. Go and see Matt...






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Nickp

posted on 23/9/17 at 04:05 PM Reply With Quote
quote:
Originally posted by jeffw
Spring rates will not matter that much if you are running rubbish dampers. Go and see Matt...


I am

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jeffw

posted on 23/9/17 at 06:57 PM Reply With Quote
Then do another TD and be amazed at the difference. Set of Protechs with the correct damping and spring plus Procomp setup and it will be a different car.






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