after throttle bodies, what next?

[Richard J Darnell]

For a 1.6k SS (about to get TBs/airbox + ECU) what is the next logical upgrade?

 

From these pages I understand TBs + ECU will give me about 150bhp (maybe a bit more because the head is ported)

 

What should I be thinking of doing next? My guess is that I should get a new exhaust (I have the standard roadsport exhaust) and then some new cams, but is this the best way to go?

 

I have a 180bhp target in mind but I don't want to spend too much otherwise I might as well buy an SLR!

[Jason Plato]

I would start keeping an eye out for a vvc head second hand , and getting it ported , once the new head is modified you can fit cams followers , shims etc as one big job . Swiftly followed by forged pistons .

The competition exhaust you already have so no further work required there teeth.gif

 

This way you can keep on the road whilst further mods are done .

 

Edited by - Dave J on 22 Feb 2002 13:54:15

[Johnty Lyons]

What exactly is the roadsport exhaust ? The std Caterham exhaust is crap you need a decent 4/2/1 or at least the 4/1 competition exhaust. to maximise your gas movment, if you have this then go for cams and you will on a non vvc head get at least 170/180 Brake.

jj

[oilyhands]

The standard head properly ported with bigger valves can carry enough air for over 200BHP, the VVC head has a higher ultimate potential but will be more expensive to procure and modify, plus it needs a more expensive inlet cam, a blanking kit, mods to the end o0f the head to accept the distributor cap and mods to the leads to allow them to reach the plugs since the head with cam ladder is thicker. Dont get me wrong I've done at least 35 VVC head conversions but if your requirements are 200BHP or less, you could start with the head you have and save some money, especially on a 1.6. A well ported big valve K16 head with 1227 cams and the correct calibration should be good for 195-205BHP, more if you are lucky.At that level the VVC head doesnt offer much advantage, the next level up however...

 

Oily

[Jason Plato]

"A well ported big valve K16 head with 1227 cams and the correct calibration should be good for 195-205BHP, more if you are lucky" ............ ohhh I hope your right oily wink.gif ..... find out tomorrow teeth.gif

I've got everything crossed !!!

Dave

[Richard J Darnell]

when i say roadsport exhaust I mean the standard 4-1 exhaust with the collector under the bonnet

 

what i want to know is what is the power penalty if i have keep this "cr@p" exhaust?

 

if it means only losing 5bhp i might save my money

[Jason Plato]

Oh I was mistaken - I thought all roadsports had the competition system ??

 

Dave

[Peter Carmichael]

That exhaust is losing you power all through the rev range. You won't get 150BHP with it still in place.

[Mick Day]

That exhaust is losing you power all through the rev range. You won't get 150BHP with it still in place.

I can confirm that: going from the standard to a 4-2-1 gave a considerable increase.

[JP]

Not sure what the numbers are relating to changing the exhaust, but the change to the torque curve was immediatley obvious with mine. The engine instantly came alive.

James.

[bl0498]

Guys,

 

Perhaps asking a dumb question but can you achieve a power improvement on a non-TB car using the standard Rover EMS (EU3) simply by changing the standard 4-1 (under bonnet collector) exhaust for either the long pipe 4-1 or the 4-2-1? If so which exhaust is better?

 

Many thanks,

 

Brian

[Rob Walker]

Brian,

 

No its not a dumb question. The long primary 4:1 will give the biggest overall power increase and the 4:2:1 will give the best compromise between peak power and mid range torque. I would go for the 4:2:1 if your budget allows. You will have to enlarge the hole in your side skin though. The short primary 4:1 has been shown to strangle performance even on standard unmodified K`s.

[bl0498]

Rob,

 

Thanks for that. SO I can improve my 135bhp by simply changing the exhaust? Roughly what bhp gain? Will the MEMS EU3 map cope with this change. Do I retain the cat? Sorry - there are always more questions!!! Don't tell me - this is an expensive upgrade!!!

 

Brian

[JP]

blo498,

I think you'll probably struggle to find hard data about bhp difference. The big difference is in the torque curve. If yours is standard like mine I found that there was little power below 4000-4500 revs. First drive with new exhaust was an eye-opener. The power comes in about 1000 revs earlier (or at least that's what it feels like)! The whole engine seems to rev much more freely. It is worthwhile upgrade.

I have the standard ECU in mine (1999 probably EU2). I've kept the lambda sensor in one of the primaries in side the engine bay. I've been told it is ideal to have the sensor at the junction in the collector but this means it has to be outside the car - ugly and bound to be broken.

I have kept the cat because I'm unsure about emmisions rules and my first MOT comes up shortly. There is not enough room to have a long primary exhaust with 4-2-1 collector and cat down the side of the car. Therefore I've had my exhaust made for me (cheaper than caterham). I've got a 4-1 into my cat'd silencer but wold like 4-2-1. I had the manifold made such that the pipes emerge from the engine bay in the right arrangement to take off the 4-1 collector and replace it with a 4-2-1 collector and cat free silencer. (Certain pipes need to be paired for the 4-2 bit.) The plan is to have a second lambda takeoff at the collector. In response to an earlier thread oilyhands suggested that you only need the lambda for ECU setup - it that then be removed (with the M3DK). When I get my Emerald ECU this what I'll do and blank off both lambdas.

Oh, yeah - my custom s/steel manifold was £350 fitted.

Hole in the sideskin needed some tidying, otherwise job was a good'un.

[caterhamnut]

rough cost of a 4:2:1 for 1.6K SS ?

[R500 CYA]

I've just been down this road, so I can give a fair idea.

 

My 1.6 SS has had Lumemition TB's and a new ECU fitted, together with a new 4-1 exhaust.

 

The car is now producing 156 hp but the biggest change is in the power delivery. The torque curve has been completely flattened out and the bhp is supplied in an almost linear sense from 3 to 8000 rpm.

 

Peak power is now at 8000 rpm and peak torque at 6500.

 

The exhaust is a hotch botch of Caterham primaries and collector with a tech craft repackable silencer. I chose this system so I could be assured a better exhaust flow without the noise problems that come with the standard race system. The net effect has been a 20 hp gain overall and a 3dB noise reduction. Very pleasing.

 

Subsequent conversations with Dave Andrews and track driving has shown that the limitation now are the cams. The torque and bhp delivery in the mid range make considerable difference, but the top end is still uncomfortable.

 

Dave has suggested bigger valves, cams and porting. This should give me 185 to 190 hp, which I think will suffice!

 

Hopefully he'll be starting in April, so I'll keep you posted.

 

Nick

 

[R500 CYA]

Oh, A&T, the exhaust ended up costing me £1,000 (including fitting and adapting the collector)!!!

 

This is far from typical though and I believe c. £600 is more normal.

 

Nick

[JP]

I'd second that. I'm expecteing to pay £250 - £300 for a 4-2-1 collector and s/s silencer.

[Rob Walker]

You will be lucky.

[CHRIS GALE]

I've just had the SLR 4-2-1 exhaust fitted, but have noticed a slight loss of power midrange with more of a kick higher up the revs. This appears to be the opposite of other 4-2-1 ugrades.

I also had fitted 6 speed and L/W flywheel at the same time, could these upgrades be the course.

Also is it possible to adapt the std 5" silencer and cat onto the 4-2-1 primaries for MOT purposes.

 

C7 CJG.

 

 

[JP]

Rob,

The price doesn'y include manifold as I already have that. It makes the full system price about £600. I not planning on having to rely on luck!