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[fiecos dan]

The venturi's on my carb are 21/23 at smallest part.


The turbo is a full T25,

[BUTRE]

The venturi's on my carb are 21/23 at smallest part.


The turbo is a full T25,

What carb is that? weber? what model?

21/23 are small venturis for a 1.6 engine. You should go for 23/25 or even 26/27mm venturis. When changing venturis rejecting the carb (seting up the main jets, idle jets, etc) must be fine tuned!

Also, you cant grind open the std venturis! It will kill the flow momentun!

[fiecos dan]

It running Std xr2 tt carb, TLDM.

i dont need to up the carb, as Reno 5 boys run 300 bhp on a carb thats only got a single Venturi of 25mm.

Thats my next mod, a R 5 carb.

[BUTRE]

It running Std xr2 tt carb, TLDM.

i dont need to up the carb, as Reno 5 boys run 300 bhp on a carb thats only got a single Venturi of 25mm.

Thats my next mod, a R 5 carb.

25mm venturi for 300bhp... hard to belive but ok.

There is a so called Grp A carb for the GTT. Never found out what it was about... for this you can go to k-tecracing since they are very well known for their GTT's.

[fiecos dan]

I thought the same thing,


But i've spoke to a couple R5's boy's, inc the tuner, and mate of the fastest R5 in the country.

He mates runs std carb, and 11.4 @ 123mph @ the pod,
and his runs 11.6@118mph.

And they both used to have a GpA carb, and so did most of the fastest 5's, but they have all gone back to Std, As gpA's have a problem of always running lean @ high RPM, (same as mine)

But to get the flow they run 40psi boost before the carb, = about 30-32 psi after the carb.

[fiecos dan]

Also spoke to K tec,

They told me a std is only good for 190 bhp, and a grp A one for 250 bhp,
But he wouldn't tell me if they can get 12.0:1 AFR thro out Rev's on full boost, and i asked 3 times, so i guessed they most run it rich mid range to get the fueling @ the top.

Which then is no advantage to me to change over.

[BUTRE]

I've always been into Renaults (its a family thing) but I hate the GTT engine! Very bad efficency so...

The idea of getting a bigger venturi is that you wont lose that much boost after the carb but you'll have slow air flow speed when off-boost (at low revs if you use an huge turbo). You can always use bigger main jets to help mid and top revs mixture. If that doesnt help, take a look at your fuel pump because the bigger main jets can be drying the carb "tank". Like the GTT, the std fuel pump only flows for 190BHP and everyone blames the carb for lean mixtures at high rpm when going 190BHP+

Another thing that is always forgotten is the 90º bend the mixture has to make just after the carb.
Quick acelerations and high fuel injection on carbs tend to make the fuel drop off suspension at that bend "pooling" the manifold's floor. This happens because the fuel is not yet well homogenized with the air flow.
To cure this get a bigger manifold plenum by fitting a spacer plate between the manifold and carb. The carb will sit higher so check if the bonnet closes.
This may give you less throttle response depending of the thickness of the spacer plate.

[fiecos dan]

Cheers mate,


But i've done everything on my carb, Also my fuel pump has enough flow for 500bhp on the pressure it runs on my car.


But the Mani mod, sounds intresting. might have a play. But i have raised the carb before, but might try more.

[BUTRE]

I've tried rising the carb/SPI a couple of times. Some times it works and some times I lost throttle response with no gains whatsoever.

This only aplies to wet manifolds (manifolds that flow mixture air/fuel).

[fiecos dan]

Other option that someone sugguested, Bike carbs, running 38mm venturi's each, but need to find some info on them.

[BUTRE]

I never tried bike carbs but was tempted once and found out some issues right away:

- small fuel bowl can get you in trouble
- difficult to setup properly due to not being available that much main jets, idle jets, etc
- not all have screw mixture

Going one barrel for each cyl is the best mate.
You dont have that much room to have a pair of DCOE's with a custom good plenum. Solex ADDHE/DDH 40 like the ones found on the AX Sport are smaller than the DCOE but the setup can be tricky for not being available lots of jets.

Why not weber IDF (downdraught) 40 carbs? They use alot of DCOE stuff that is easy to find. Never saw or heard anyone using them on a turbo engine, but I belive that it can be done

[fiecos dan]

i had a set of down draft 40's years ago, and decided not to, as they are bad enough to tune/going out of tune on a N/A engine,



i just thought as bike carbs are more modern and Jap, they would be better than Webbers.

Been offered a set of lotus twin 45's, already modded to fit a cvh, for £300, but once again noone can tell me if they will have midrange fueling problems.

[BUTRE]

DCOE's, IDF's, IDA's, DHLA's, etc will go out of tune pretty easy. You'll have to be always alert and balancing them over and over again.

Can't think of anything else when keeping using carbs... just try the GTT carb on std venturi and rejet it to your engine. Also try getting the carb higher and check fueling at low and mid rpm and compare the power curves.


I'm guessing you dont want to go EFI. Proper inlet manifold with a good plenum design with a low-cost ecu (megasquirt for example) would give you full control of fuel and ignition over the entire rev range.

[fiecos dan]

i know inj is best, as i built and mapped my cossie,

But i want to keep the TT with its root's of a carb turbo.

[fiecos dan]

Another update from the last 2 weeks,


Ok, i've played alittle attention to the engine bay of the xr2tt,

i've made the 2nd ss boost hose,
Polished the plenum, Boost hoses, and Ex mani heat shield.
i painted the strut brace, and wiper motor cover,
replaced all the fuel lines for new,
Full service.


Some Pic's of my s/s boost pipes i made for the tt,






Pic's of my new downpipe, and heat shields





And some Engine bay pics,







I've also striped the carb, modified it to help flow,
modified the plenum chamber, by opening the restrictive places out and flowed it.
i tried a few other mod's with the carb to try and sort the mid range over fueling, but with no joy.

i Also rejetted the carb for top speed runs, but reliesed the engine wouldn't rev past 6300 rpm in top gear, which i have put down to the hydrolic tappets.


On Tuesday i went to Performance Ford mag's Fiesta thrash @ brunters,

it rained before i got a chance to do some sprint time's, so was abit of a let down.

The mag will be out in 2 weeks time, so yourll be able to see my wet times in there.


And 2 nights ago i raced my brothers 300-330bhp Pulser gtir, and a mates Evo 4, They were identical to each other from 40 - 120 mph, and i was 2 car lengths behind, ( i was running at 15psi, 185 bhp / lbft spec.)

[BUTRE]

I really like your XR2. So simple and sticking to the basics on tuning an engine. Excelent stuff!

btw, how laggy is the CVH36 cam? Have you already got a power graph from your last dyno online?

[fiecos dan]

cheers mate,

the 36 is meant to be more torque'ie than the 35, with aliitle less bhp,


but when i changed the cam, i fitted a stg3 head, with larger valve's, so cant say wot the 36 cam is like to my old 35.


full boost of 23 psi is hit around 3400 rpm, so very laggy for a t25, but that is most prob down to the .64 ex housing.

[fiecos dan]

Picked up a spare set of 4 Zetec S wheels (same as i run on road)
fitted with part worn Avon 170/550/15 slicks.
Perfect for trackdays.

Measured both a Avon slick 3/4 worn, and a Dunlop 195/45 15 road tyre with 4mm tread, both fitted to Zetec S rims, and pumped up.
O/A hieght = 551mm Slick, 544mm Road tyre,
O/A width = 185mm Slick, 195mm Road tyre,
Tread width = 170mm slick, 165mm Road tyre.



Aiming to Go to a Trackday in the xr2tt @ Lydden Hill, Kent on the 22nd of July.

Need to,

Build and fit a gated Sump to cure oil surge problem,
Refit my Mocal 16 row oil cooler, i took off 3 years ago.
Fit EGT gauge, (boss already fitted in down pipe)
Modifie, and fit a Reno 5 turbo carb, and rejet,
Replace Valve springs,followers and check cam for wear,
(as its running noisie, so i think the cam's fukced itself due to oil surge problem),
Design and make front Castor adjusters, and set to 2.5 neg camber, and 3-5 degree castor, and set toe,
Shim out rear beam, to add Neg camber, and set toe.

So got my work cut out, but should fly once all done.

[BUTRE]

Since my FRST is going also to the thrills of trackday's, I was wondering if the CVH sump suffers from oil surge... the oil pickup I mean. Dry sumps are expensive and I can't even find a kit for the CVH.

But one thing that is really bothering me is the wishbones. Need 2.5 castor, be able to adjust camber from -0.5 to -2º and get rid off torque steer
Zoo motorsport ones are just too expensive!

Are the XR2 wishbones alot different from the FRST ones?

[fiecos dan]

I dont know wot FRST wishbones i like,

the front cambers all ready set @ 2.25 neg, but castor not.


My car suffers mega surge problems.

[BUTRE]

I had -1.5 front camber and it was bad for grip on straight line and braking. Also this gave me plenty of oversteer when cornering. Had -0.5 camber at rear.

Usually to avoid oil surge ppl go 1/2 litre of oil above the max mark on the dipstick. How does the CVH engine handle this? Is it advised to do it on the CVH?

[fiecos dan]

Thats a NO no on most engines, filling over max, as will course smoke on most, but i haven't tried it on a CVH.

i done my best 1/4 sprints on 1-2 neg camber, and at 2.25 degrees neg, it dont seem much worse in straight line than no camber on either of my cars when i tested it, But at 0 camber they were both really bad for under steer.

[fiecos dan]

Ok today i took sump off, and Just finished making a baffle/gate system,

Its a trail attempt, but Should do the trick,






Here's my trackday wheels and Avon slicks

[fiecos dan]

Been out and tested the sump,

And its alot better on right hand corners, braking and accelarating,

But left hand corner's are still the same, oil pressure dropping to 30psi from 60psi,

So gonna have to try again

[fiecos dan]

Tonight i been out hard testing for 10 minutes around a local track (the loop) , and even tho there still was surge on left handers, i didn't get any problem with tappets colapsing like i used to.





Yesterday, i set the car up in my garage, so it was level all round

Then i measured, 4 wheel Toe, camber and castor all round

It come out like this

Front, modded camber, and poly bushes.
toe = 2mm out,
camber n/s = -2' 30", o/s = -2' 15"
castor n/s = +0' 30", o/s = +0' 23"

Rear, Still std bushes and beam.
Toe, n/s = in 2mm, o/s = out 3mm = total in 1mm toe out.
camber, n/s = -0' 8", o/s = -0' 11"




After a day of playing with the suspension to day,

including

- shorterning the tie bars by 17mm each side, making new washers and fitting new poly bushes,
- cutting and welding the n/s tie bar to miss the gearbox casing,
- cutting the front arches and body kit to stop any tyre scrub ( as now the wheel sits 2 mm away from front of the arch)
- going for a drive to settle all mod's and bushes.
- Checking Toe and adjusting to no toe, checking camber and castor.
- and finally going for a hard test drive round the local track ( the loop)

It does seem to understeer less, but it still does round roundabouts whilst pushing it.

The setting now sit at

Front,
0 toe,
camber n/s = -1' 38", o/s = -1' 23"
castor n/s = +3' 00", o/s = +2' 45"

Rear, Still std bushes and beam.
Toe, n/s = in 2mm, o/s = out 3mm = total in 1mm toe out.
camber, n/s = -0' 8", o/s = -0' 11"

So now i'm gonna put more camber on fronts, and fit new poly bushes on rear and space beam out to get even toe of 0 toe, and put camber to -1' 30"

[fiecos dan]

Ok, small update.

Here's a pic of the cossie last week looking very un cared for,





On my tt,

i fitted a 16 row mocal oil cooler,
changed the brake fluid, and fitted new front ferodo pads






2 weeks ago i done a Lydden hill Trackday in my tt, on 22/7/06

had a good day,

Run it at 18psi for the first 5 sessions, done 1 session at 23 psi, and the last 2 sessions at 14 psi.

Car behaved, except a few little problem, i run a 51.39 PB on my lap timer in my tt

Carb was flooding left hander, so only half throttle could be used till half way up the hill,

Avon slick Tyres i was using werent warming up till the last couple of laps of the session, so times got faster and faster till the end of each sessions.

Coolant temps too high allday. Even removed the Stat on 3rd session, and didn't change anything, By 7 mins into the sessions the fan had cut it, and didn't cut out till 5-10mins after the session had ended.

But understeer was very present, My brother was also doing it in his Pulser, But on the last session he took mine out, and couldn't believe the amount of under steer, (as he always sed his has bad underesteer)

I got the pressure's correct after the 4th session, so the tyres were even temps across the tyres ( or well as even as they would get)

But suspension needs changin,


Tyre pressures hot were

F n/s 27psi, 18.5psi cold, temps 73-79oC
F o/s 24psi, 16psi cold, temps 71-77oC
R n/s 23.5psi, 20psi cold, temps all 51oC
R o/s 21psi, 17.5psi cold, temps 45-49 oC

My front o/s slick at the end of the day, was checked to sessions before the end, and was fine. but my brother drove it on the last session, and locked the front wheels going into the hair pin once.

[fiecos dan]

3 days ago i took the suspension apart, so i could rise the TCA mounting at the chassie, so the tca is slopping down, so harder it corners the more camber is added,
where as up till now it run the opposite way due to being lowered 75mm at the front.


End result,

O/S front,

chassie TCA mounting holes has been moved up 16mm, and out 10mm,
Tie bar has been shortened a total of 24mm.


N/S front,

Chassie TCE mounting holes been moved up 18mm, and out 10mm,
Tie bar has been shortened a toal of 26mm.


The reason why i did different amounts for each side is because
The tie bars are different, so had to do it to get the same amount of castor each side.
And the chassie holes are different to get the TCA's sitting the same, as well as to help once the driver sat in it.


Heres some pic's of my work and mod's.

Cut down Tie bar, and new H/D washers to stop them bending like std ones do,






Where i had to mod the N/S tie bar to miss the gearbox,






My modded Tie bars and TCA's





My modded TCA's, 1st i had to cut, and strengthen them to miss the chassie where i haved the chassie mounting higher, then i had to cut and strentghen them so they where 20mm further forward, so they would mount with the new shortered Tie bars with out adding strain to the TCA mounting bush, and then slot the hole to line up with the Tie bar.









The new, higher mounted TCA's.







Next mod, will be to fit insiti adjusters on the TCA's when i get a set.

Heres a pic with the car back on the floor.
Some major arch removal had to be done to stop rubbing.

[fiecos dan]

The way i measure my, toe, camber and castor, is all done on the cheap.

firstly i level the ground off in my garage, using boards, i then drive the car onto them,
the front wheels also site on home made Turning plates (not in pic's as made them at the weekend), and the rears are siting on boards to keep the car level all round.





i then made 2 stands, which are made to the same width, and designed to have string laid between them, the string has wieghts on them to keep them tensioned,





The strings are then placed in TRUE parrel with all 4 hubs on the car, by measureing to the hubs.






i then measure accurately from the string to the front and rear of each rim ( wheels have to be straight)
This Give me the 4 wheels tracking.







To measure the camber i use 2 devices i brought from demon tweaks, all in all about £80 -90. One is a camber/castor plub gauge, the other is called a Toe string gauge.

i place them on the wheels like the pic below, and read the measure ment for camber, and do this on each wheel.




To measure the castor, is abit more complexed, as each front wheel needs to be turned 20 degrees on each lock, and then the measurement worked out from both readings.
To do this i had to make a set of turning plates for the steering to be able to turn on the spot, with out resistance and pressure on any bush/mount.

To measure the 20 degree lock, i have made a template i use, i set the template up on the floor parrell with the car using the Tracking strings, then turn on each lock till its at 20 degrees from straight, to do this i use a straight rule against the tyre about 100mm above ground, so the tyre is in its true form (as at bottom the wieght of the car puts a bulge in the tyre) Then eye thro the rule to the template,

It might sound un accurate, but i've tested it back to back, and get the same results each time. But i will once sorted the car, send it to a mate who will check it all on his works 4 wheel laser allignment setup (over £15k worth)

[ianFRST]

[heeman10]

You don't half put the hours in on this car to make it perform on track! I take it Lydden is mostly right-handers then Out of interest, are there any more-expensive cars you surprise with the Mk2 yet? Is it that far advanced?

[fiecos dan]

You don't half put the hours in on this car to make it perform on track! I take it Lydden is mostly right-handers then Out of interest, are there any more-expensive cars you surprise with the Mk2 yet? Is it that far advanced?

Your'll be suprised.

At the last trackday, my brother was only 1 second a lap faster in his 300 bhp road/trackday pulser,
on moulded slicks, good suspension, and Large brakes, set up geometry.

Down the straights we were side by side, it was the braking, and tight corners i lost out on,

Also there was a 500bhp Track pulser, running low boost, so about 400 bhp on day, Full Tien suspension, fully set up by Leda, 048 yok tyres ( at Brands he was slightly faster than my Cossie round the indy cicuit)
and he was slower than me in the morning, but by the end he was 1/2 second faster than my brother, so 1.5 seconds faster than my xr2tt.

Lydden is a 1.3 mile circuit, all but 1 are right handers.
takes me 51.3 seconds in my xr2 running 185 bhp, takes my unsetup cossie 48 seconds at 430 bhp,
And my old Man is a Paid instructor there, and does 44's consistantly, with 44.2 being his fastest. But he is on a Road/trackday on road tyres, R1. and He's raced at Lydden since the late 70's, on a 180mph, 750cc 2 stroke ex british championship winning bike (1978-1982) then started doing trackdays there again in 1996, and now does 20+ trackdays there a year.

To put in consideration, Most of my Dad's mates, who like to think they are fast on the road, Do 47's-50's on Thier 600-1000cc super bikes.

[sexybitchhannah]

both look very tasty mate nice work

x hannah x

[fiecos dan]

thankyou,

[heeman10]

Sounds like it's all paying off then! Gotta say the Mk3 is still by far my favourite though, I love that thing

[fiecos dan]

Yeah its a good crack, But under steer is still to present,


once i've stopped playing with the mk2, the cossie will be back, better then ever.
No more power tho, just refined, and the geometry will be sorted also.