Top Speed at the track ?

[Klasik-69]

I see in your signature that you own (owned) a Z06. I also own a Z06 as well as a Caterham. I track both of them. The truth is that, on a track, the 7 will not be able to stay with the current generation of supercars. It just doesn't have the top speed. And the "big" cars are no slower in the corners either. I have always said that if there is price money for the fastest lap, I will be crazy not to bring the Z. The two cars have different personalities. Accept that and just enjoy the way it drives, regardless of what the top speed is.

 

I still own the Z06 and run occasionally at the track. However, as you know, $1600 for a set of Hoosiers, $490 for a set of Carbotech pads, 60 to 80 gallons of high test fuel, it adds up to a pretty expensive weekend. Thats's why I got the Miata. Wow, talk about slow. I have time to call the wife between turns and ask what's for dinner, play solitaire on my Iphone, etc. The R300 is a blast, an absolute kick in the pants, makes my heart race just thinking about it. Its more fun that anyone should be legally allowed to have................except for the top end. Such is life.

[Klasik-69]

I have some solid specs on the transmission and rear end for those of you analyzing where I am and where I could improve;

 

Standard T9 5 speed

1st - 3.65:1

2nd - 1.97:1

3rd - 1.37:1

4th - 1.00:1

5th - 0.82:1

 

Rear end ratio is 3.62:1 according to Jon @ Caterham. He indicated that 3.92:1 is an available ratio but more people are going from the 3.92 down to the 3.62 than the other way around. Street vs track use ?

 

Currently from a rolling start, the car will literally break loose the rear wheels with ease in 1st, 2nd and if its a cool morning, 3rd as well under full throttle.

[Kitcat]

Terry, the Cat dealer in Canada reports more speed w/top up/doors on. I found switching from full windshield to Brooklands was worth abt 5 mph, and I got there faster. And turn head lights backwards or sideways (If nothing else it will make you feel faster:)). And, while it's a brick, at least the the se7en is a small brick and a lousy cd times a small # is still small.

 

Check the dyno-sheet smackdown thread for some real world numbers for our engines. Those of your spec seem to be cranking around 145-160 hp at the wheels.

Edited January 25, 2012 by Kitcat

[Croc]

I have some solid specs on the transmission and rear end for those of you analyzing where I am and where I could improve;

 

Standard T9 5 speed

1st - 3.65:1

2nd - 1.97:1

3rd - 1.37:1

4th - 1.00:1

5th - 0.82:1

 

Rear end ratio is 3.62:1 according to Jon @ Caterham. He indicated that 3.92:1 is an available ratio but more people are going from the 3.92 down to the 3.62 than the other way around. Street vs track use ?

 

Currently from a rolling start, the car will literally break loose the rear wheels with ease in 1st, 2nd and if its a cool morning, 3rd as well under full throttle.

 

A T-9 box was designed to get a Ford Capri (a UK model not the POS sold in the US as a convertible), or a Ford Sierra/Mercury XR4i. So first gear is useless for us in a seven.

 

The UK Caterham racers using a Type 9 gearbox and a 3.62 diff will generally modify the gearbox with help from BGH with a long first and a close ratio gear set of the following ratios

1st - 2.39

2nd - 1.54

3rd - 1.21

4th - 1:1

5th - 0.87

 

For comparison the Caterham 6 speed box has the ratios of:

1st - 2.69

2nd - 2.01

3rd - 1.59

4th - 1.32

5th - 1.13

6th - 1:1

 

The ratios tell the story how your standard T-9 box is holding you back from accelerating quicker and from keeping the engine in its power band.

 

I have seen on Blatchat that a 3.92 diff ratio is more commonly paired with a 5 speed T-9 box whereas the 3.62 diff ratio pairs with a 6 speed box.

 

Here is a thread on Blatchat discussing the pros and cons of this further:

http://www.blatchat.com/t.asp?id=208870

http://www.blatchat.com/t.asp?id=201170

 

Switching gears (pun intended ) - Other aero tips from the Caterham UK racing series - cover up the passenger side of the cockpit so that air flows smoothly over. You can do this with the tonneau or buy a fancy cover from Caterham, Fluke, etc.

[sdca7]

My highest speed in the R500, with a Caterham 6 speed, is 138 mph using GPS at the end of the straight on a NASCAR oval at Fontana. It was not at redline yet, but didn't seem to be acceralating much any more. I keep my foot flat through the bank. The GT-R's hit about 160 to 175 at that point in the track.

 

My car was dynoed at ~215 at the rear wheels, fwiw..... but all dynos are different.

 

Justin

[dallasdude]

For maximum speed you want to be able be at the power peak of your engine at what the maximum speed for the car is. I think 202 hp at the crank is going to push a Caterham to about 130 mph or so. I suspect the hp peak for this engine is about 7000 rpm, although the dyno will tell the real story. This calculation shows that in fourth with a 3.62 and a 185/70-13 (or any 1815 mm tire), you are about optimized. If the power peak is above or below 7000, you could benefit from a change in gearing to be at your max hp when everything equalizes (hp vs drag).

 

The bad thing about using this combination on the track (3.62 with the stock T-9 gearset) is you have to use second at some tracks.....and the gap from second to third on a standard (non BGH or Quaife) T-9 is big. The drop from third to fourth also hurts because the drop occurs at at a higher speed with the 3.62 and hurts acceleration getting to the top speed.

catgearing.pdf

[blubarisax]

I have to tell you all that 125 is plenty fast in a Caterham. Last year the GPS had me at 141 driving the full tri-oval at Pocono Raceway. Full windscreen and 500#' of passengers! That was as fast as I want to go. Thankfully I was drafting behind a Porsche GT3!

[hoefi]

I still own the Z06 and run occasionally at the track. However, as you know, $1600 for a set of Hoosiers, $490 for a set of Carbotech pads, 60 to 80 gallons of high test fuel, it adds up to a pretty expensive weekend. Thats's why I got the Miata. Wow, talk about slow. I have time to call the wife between turns and ask what's for dinner, play solitaire on my Iphone, etc. The R300 is a blast, an absolute kick in the pants, makes my heart race just thinking about it. Its more fun that anyone should be legally allowed to have................except for the top end. Such is life.

 

I hear you.

 

Tire costs, pad costs and fuel costs is nothing compare to dropping an exhaust valve in that $12,000 Chevy motor.

 

Had a Miata many years ago also. Ran it at Laguna once for the fun of it. It was painful.

 

Good luck with your quest for a higher top speed.

[Klasik-69]

A T-9 box was designed to get a Ford Capri (a UK model not the POS sold in the US as a convertible), or a Ford Sierra/Mercury XR4i. So first gear is useless for us in a seven.

 

The UK Caterham racers using a Type 9 gearbox and a 3.62 diff will generally modify the gearbox with help from BGH with a long first and a close ratio gear set of the following ratios

1st - 2.39

2nd - 1.54

3rd - 1.21

4th - 1:1

5th - 0.87

 

For comparison the Caterham 6 speed box has the ratios of:

1st - 2.69

2nd - 2.01

3rd - 1.59

4th - 1.32

5th - 1.13

6th - 1:1

 

The ratios tell the story how your standard T-9 box is holding you back from accelerating quicker and from keeping the engine in its power band.

 

I have seen on Blatchat that a 3.92 diff ratio is more commonly paired with a 5 speed T-9 box whereas the 3.62 diff ratio pairs with a 6 speed box.

 

Here is a thread on Blatchat discussing the pros and cons of this further:

http://www.blatchat.com/t.asp?id=208870

http://www.blatchat.com/t.asp?id=201170

 

Switching gears (pun intended ) - Other aero tips from the Caterham UK racing series - cover up the passenger side of the cockpit so that air flows smoothly over. You can do this with the tonneau or buy a fancy cover from Caterham, Fluke, etc.

 

I guess from what you're saying, what I posted for ratios may not be the right ratios. Now I'm not sure what I have. I'll have to jack up the car, mark the driveshaft, shove it in first and rotate the engine until the shaft turns 1 turn and see how many engine turns it took to be sure. I would think if I know 1st gear, the rest follow true to form (???). Also from the ratios you show on the 6 speed, this would work a lot better for track use as it gives me a wider range of choices to keep my engine at its peak power band. Oh God, more $$$. Better not buy another tranny, the wife will leave me, and that will cost me a lot more than a tranny !!

 

My perception on the track with the car: Acceleration is excellent in 1st, 2nd and 3rd. 4th is a bit of drop off. On some tracks (Sebring turn 7) I do drop into 2nd but for the most part its only 3rd and 4th, even at Barber. If I go into 5th, may as well slam on the brakes (hey, a good emergency braking option).

 

My thought (feel free to kick me to the curb): If I help aero a little, lower the rear ratio to allow me to use 5th, overall trackability will improve (????) Please keep in mind I took off the 13" wheels with the Avon CR500 tires and using the 15x7 wheels, which likely didn't help me on the top end since I increased my overall wheel diameter.

Edited January 26, 2012 by Klasik-69

[Klasik-69]

I hear you.

 

Tire costs, pad costs and fuel costs is nothing compare to dropping an exhaust valve in that $12,000 Chevy motor.

 

Had a Miata many years ago also. Ran it at Laguna once for the fun of it. It was painful.

 

Good luck with your quest for a higher top speed.

 

Yeah, :iagree:. How many times have you heard the Miata guys say "its a momentum car and it will make you faster !" Yeah, I know how it will make me faster, I jump into the Z06 or the 7, and then I go faster. Actually, I'm in the process of installing a turbo in the little bugger (Miata), and that will make me faster too. Ever notice the Miata owners are the ones happy doing 55 mph on the interstate when the speed limit is 70.............give me a breakkkkkkkkkkkk.

[dallasdude]

If you are going to use fifth, even a .87 fifth with 15" DOT tires you probably need a 4.11 with a Zetec for maximum speed. None of the factory Sierra rears I think came with anything below a 3.92. Raceline has sold a 4.11 and some other lower ratios, but right now they are out and looking for another supplier to manufacture them. A group buy would certainly help them. If you have your tire diameter I'd be glad to run the numbers on for you for your actual current combo or an alternate.

 

I'd see where the dyno says your power peak is and be sure you are optimized. Aero tweaks here and there will certainly help, but it would be good to get input from other people on this board to see what 140mph takes. I would think its probably over 250 hp which is almost out of reach for a streetable NA Zetec (TurboFocus1 is the expert on that), but a moderate build for a Duratec.

 

All other things being equal, about 35+ hp more and 35 pounds less weight for a Duratec vs Zetec.

[Klasik-69]

If you are going to use fifth, even a .87 fifth with 15" DOT tires you probably need a 4.11 with a Zetec for maximum speed. None of the factory Sierra rears I think came with anything below a 3.92. Raceline has sold a 4.11 and some other lower ratios, but right now they are out and looking for another supplier to manufacture them. A group buy would certainly help them. If you have your tire diameter I'd be glad to run the numbers on for you for your actual current combo or an alternate.

 

I'd see where the dyno says your power peak is and be sure you are optimized. Aero tweaks here and there will certainly help, but it would be good to get input from other people on this board to see what 140mph takes. I would think its probably over 250 hp which is almost out of reach for a streetable NA Zetec (TurboFocus1 is the expert on that), but a moderate build for a Duratec.

 

All other things being equal, about 35+ hp more and 35 pounds less weight for a Duratec vs Zetec.

 

The tire size I use is the 205-50ZR15 which if my calculations are right is about 23 inches. As far as rear end ratios available, you're quite correct that the 3.92 is the lowest ratio available. In fact, according to Jon @ Caterham, its either 3.62 or 3.92 at this time. There could be some old stock laying around on either side of those ratios. The 6 speed gear box seems more in line for this car and what I intend to do with it.

 

No doubt, the Duratec is the better option unless you already have the Zetec (which I do). Yes, I thought about pumping up the HP and talked to William at CFM in Orlando about cams and pistons. By the time you buy the parts and have the head re-worked, cost is likely to be around $6K and the HP gains may be around 40 or 50 HP. Or about $120 per HP. And as you pointed out, how much HP will be needed to get to 140 MPH ? I don't even want to try to get to that level. 130 would suit me well, and 125 would make me smile. If I could go on a diet, I could lose maybe...........well, never mind, it may be easier to buy the horsepower than to gain the willpower.

 

I contacted Cosworth for engine quotes. A 290 HP 2.3L Duratec was around $18,000. I could buy a LS9 with 638 HP for less but, yes I know, it won't fit in the R300, and I don't have an extra $18,000 laying around anyway.

 

I'm going to be running this car in the SEDIV TT and I think if I can get a little more on top, I should be in good shape. I'll need to sharpen up my corners to make up the other shortcomings.

[Klasik-69]

I would be remiss if I didn't thank all the guys who chimed in to help me. It also gave me an opportunity to kind of meet you guys. So to dallasdude, croc, rnr, kitcat, yellowss7, KiwiBirkin, JimRankin, hoefi, pi7ot, and DeanG (and anyone else if I missed someone), thanks for the help and all your valuable info. You guys are a wealth of information and a lot of fun to chat with. I hope to see you guys on a track somewhere. However, it does seem like everyone is spread out everywhere...........New Zealand being the furthest away.

[yellowss7]

Sounds like you need a road trip. Come on up for the Sevens at NJMP outing in June. So far guys from St.Louis, Cincy, North Jersey, NY, Pa and Maryland are planning on attending. The more the merrier!:party:

 

You certainly would get the opportunity to compare your car to some of the Big Dog Caterhams (Croc,Karl,Ron) Those guys have big hp cosworth Duratecs, then there are the rest of us. The driving is only half the fun.

 

Tom

[Kitcat]

Birkin USA has a supercharger option for their Duratec engines and say they are developing one for Zetecs. Mite be worth an inquiry.

[Croc]

Birkin USA has a supercharger option for their Duratec engines and say they are developing one for Zetecs. Mite be worth an inquiry.

 

Xcarguy on this forum is building a Rotrex supercharged Duratec Birkin. No idea if they can do something similar for a Zetec but I bet there is something out there for a Zetec. That would give you a hp boost.

 

I think try the aero options first with the switch to aeroscreen and cover over the passenger side of the cockpit. It would not surprise me if that gave 8mph extra top end speed alone. Certainly the car feels more responsive without the airbrake windscreen. At that point you can evaluate how far you have to go to reach your 130mph target.

Edited January 26, 2012 by Croc

[dallasdude]

Here's the chart and a graph also. Note the nice short drops especially in the higher gears on the 6 speed. The final result at max speed is however the same as your current rear end with the standard T-9 in fourth (both are 1-1 there). You'd just be able to get there faster with the six speed. On a track only car, you could probably accomplish the same thing with a Quaife Rocket.

 

I spoke with Dick Brink about the turbo Zetec when I was at his place a couple months ago and it seemed to be on the back burner, but you should check with him. He was making progress on the the Duratec.

combogear.pdf

[Klasik-69]

I spoke with several people about either a turbo or supercharger for the Zetec and was told this engine doesn't do well with either choice. Jon @ Caterham advised against it for several reasons, one of which there is very little space available for the intercooler on a Caterham chassis layout. I agree with him on that. William at CFM said it has been tried many times with big dollars spent and disastrous results. I assume he means the thing blows up. However, if you look at the Mazda 1.8 Liter engine in my Miata (don't laugh), the engine seems pretty similar. Ford and Mazda were partners for many years during the development of the Zetec and I wonder how much they do have in common. Also, the Miata engine does very very well with turbos or SC's. If I remember correctly, Scannon has an incredible Mazda powered 7 with a turbo pumping out big power. However, I believe his is the SV whereas mine isn't.

 

All that being said, I'd rather do a little here and there, more or less massage this car into getting a little more top end since the rest of the car is in my opinion nearly perfect. Its like wearing a big sneeker with wheels underneath. I would never want to compromise the handling of this incredible car.

 

Dallasdude, thanks for the graph, it really illustrates well the speed vs gear vs rear end. It illustrates the benefit of a close ratio tranny in keeping the engine in the power curve. Since I doubt I'll have the budget to change the gearbox, I may want to entertain the change in the rp of the rear end. I think Jon @ Caterham has them in stock or perhaps someone on the forum has a used one not being used that I can buy after massaging the aero of the car, should the need still exist.

Edited January 29, 2012 by Klasik-69

[scannon]

Yes, my car is an SV but I believe you could turbocharge a Miata engine in an S3 size engine bay. The manifold and turbo from an '04 - '05 Mazdaspeed Miata tucks in close to the engine and has a bit smaller turbo. Plenty of room in front of the radiator for an intercooler. I used the biggest one that would fit in the nose cone, you would have to find a narrower one to fit an S3 nose. Pictures of the installation are here: http://www.cardomain.com/ride/636168/1992-mazda-miata-mx-5/page-17

 

The Miata 1.6/1.8 engine goes back to the GTX/GTR Proteges and was designed as a turbo engine from the get go. Its a tough engine but I don't believe there is anything in common with the Zetec other than basic configuration. The Duratec was mainly developed by Mazda during the Ford/Mazda years.

[dallasdude]

The Zetec setup Birkin (Dick Brink) was working on was going to use water or water/alcohol injection because it is hard to put an intercooler in a Seven. As scannon said it can be done.

 

There a lot of Focuses (Foci?) with superchargers or turbos. I think packaging and intercooler makes people people leery about using in a 7.

 

The Mazda 1600 and 1800 engines are very robust, especially the 1800, but the thing that makes them especially nice for turbo/supercharged applications is they all come with piston squirters....nozzles that spray oil on the underside of the piston for cooling. The Flyin Miata guys can tell you way more than I know about Turbo Miatas.

 

These squirters can be added by a machine shop to other engines, but they come on Zetec SVT blocks. So if you were building a boosted Zetec, it would be ideal to start with a SVT block (with aftermarket low compression pistons and hd rods). I don't think this setup gives up much to the Miata engines for a boosted application. Funny I just moved one of each across the garage this morning and I can tell you which one weighs more.

 

With 15" DOT tires and the stock fifth, you are still probably going to be a little tall for maximum top speed with 200 hp at 7000, even with the 3.92.

 

The HP you are dealing with is not very different from what we have in our restricted Zetec SCCA EP cars. We do over 125 on longer tracks with a cage almost as big as the car.