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Zetec upgrade options?
DavidW - 16/7/13 at 09:33 AM

I currently have a standard 1.8 silvertop zetec except for 2.0L cams with ZX-9 carbs, raceline sump and water rail, decent exhaust and megajolt. The car produced 146 bhp on the rolling road and runs reliably and well despite abuse on track.

The car goes very well around the bends but I just can't help but yearn for a bit more power down the straights - No matter how hard I try I can't get faster than 107 mph the end of the back straigh at Snetterton.

I want to staick with a zetec but am trying to work out what I can do to get a little more power/speed in a fairly locost way.

I have 3.92 diff and standard type 9. I'm not really using 5th gear on track - only just getting to the rev limit in 4th on the back straight at Snetterton but I suppose 5th is quite handy for the rare occasion where I cruise on the road?

I think 175ish bhp would be enough for now?

Any ideas?

David

ianm67 - 16/7/13 at 09:44 AM

Would it not be simpler / cheaper to change you diff to a 3.6? This would give you a higher top speed before you hit the limiter in 4th...?

DavidW - 16/7/13 at 09:57 AM

Do you think it would be quicker on track as I guess acceleration would be reduced?

ianm67 - 16/7/13 at 10:11 AM

quote:
Originally posted by DavidW
Do you think it would be quicker on track as I guess acceleration would be reduced?


I guess that depends on how much torque your Zetec is producing and whether it will pull the taller gearing. It will make your first gear taller making it more usable off of the line so it's swings and roundabouts I guess.... What is the diameter of your wheel / tyre combo and the max RPM of the engine? I'll see if I can calculate the speed varaition based on the new diff ratio...

silky16v - 16/7/13 at 10:18 AM

fit a ST170 engine, VCT Delete and setup 180bhp and bullet proof engine for 7500rpm

rdodger - 16/7/13 at 10:20 AM

You might find this of use

http://www.car-videos.net/tools/speedrpm.asp?Car=Select&Num1=195&Num2=45&Num3=14&AxleRatio=4.1&Ratio1=3.13&Ratio2=2.05&Rat io3=1.48&Ratio4=1.16&Ratio5=0.97&Ratio6=0.81&Ratio7=&Redline=9000&Increment=500&B1=Recalculate

JAMSTER - 16/7/13 at 10:30 AM

what size wheels and tyres

DavidW - 16/7/13 at 10:39 AM

I have 13" wheels with 205 tyres. Shift point is 6600 which is just after peak power at 6384 which I set so as not to drop to far out of the power band after an upshift. This seems to be faster that when I was changing up at 6400.

The calculators tell me I would have another 10 or so MPH in 4th at the the shift point with a 3.6 diff but I'm not sure I'd have the power to get there?

If I went for the ST170 upgrade how much cost would I be looking at? Are throttle bodies or a swap to a 2L zetec worthwhile?

ianm67 - 16/7/13 at 10:54 AM

quote:
Originally posted by DavidW
I have 13" wheels with 205 tyres. Shift point is 6600 which is just after peak power at 6384 which I set so as not to drop to far out of the power band after an upshift. This seems to be faster that when I was changing up at 6400.

The calculators tell me I would have another 10 or so MPH in 4th at the the shift point with a 3.6 diff but I'm not sure I'd have the power to get there?

If I went for the ST170 upgrade how much cost would I be looking at? Are throttle bodies or a swap to a 2L zetec worthwhile?


My advice would be to fit a 3.6 get out on track and see if the 1.8 will pull max revs. If not, all you've incurred is the cost of the diff'. You can buy a brand new 2.0 Zetec for around £800 and on your carbs (when rejetted) you should see 155bhp+. A set of ARP rod bolts will see max RPM move to 7400rpm. Leave the 3.6 in the car and I suspect you'll be more than pleased.
Run the 2.0 Zetec on FI and 175bhp is acheivable with a decent exahust and mappable ECU.
All the best,
Ian

DavidW - 16/7/13 at 11:41 AM

So if I raised the rev limit after fitting ARP bolts, is it just a case of rejetting the carbs to make use of the higher RPM?

At the moment power drops away after 6400ish so I'm not sure how I get use of the increased rev limit.

silky16v - 16/7/13 at 11:43 AM

quote:
Originally posted by DavidW
I have 13" wheels with 205 tyres. Shift point is 6600 which is just after peak power at 6384 which I set so as not to drop to far out of the power band after an upshift. This seems to be faster that when I was changing up at 6400.

The calculators tell me I would have another 10 or so MPH in 4th at the the shift point with a 3.6 diff but I'm not sure I'd have the power to get there?

If I went for the ST170 upgrade how much cost would I be looking at? Are throttle bodies or a swap to a 2L zetec worthwhile?


engine anywhere between £250 - £400 you can modify your ZX9 carbs and manifold to fit, exhaust will bolt straight on (might need to port them alittle)
remove the VCT (£30 from america) fit a vernier pulley (£75) engine is good for 7600rpm on standard everything

but at a guess you'll create peak power at 6800-7200rpm gain a bucket load of torque

i'm using a 3.92 diff and standard Type 9 gearbox and making peak power at 7500rpm

me! - 16/7/13 at 11:46 AM

quote:
Originally posted by DavidW
So if I raised the rev limit after fitting ARP bolts, is it just a case of rejetting the carbs to make use of the higher RPM?

At the moment power drops away after 6400ish so I'm not sure how I get use of the increased rev limit.


More exciting cams would do the trick. I'm not sure whats recommended for Zetecs, but I would be interested to know!

ianm67 - 16/7/13 at 12:21 PM

quote:
Originally posted by DavidW
So if I raised the rev limit after fitting ARP bolts, is it just a case of rejetting the carbs to make use of the higher RPM?

At the moment power drops away after 6400ish so I'm not sure how I get use of the increased rev limit.


Not as simple as that I'm afraid...... The silvertop engine uses hydraulic cam followers which restricts maximum RPM. The Blacktop uses solid cam followers hence the higher maximum RPM.
A set of cams from someone like Newman or CatCams might give you another 5-6 bhp but will cost you £400 so not the best return on your investment.....
Bear in mind that your engine was once pulling around a Focus or Mondeo. In your car (550kg?) the 1.8 shouldn't have any problem coping with a slighty higher diff ratio. A diff swap would be my first port of call.......

ashg - 16/7/13 at 12:34 PM

save some money and fit an engine that makes the power you want out the box, heavily tuning an engine is a big black money hole with unreliability at the end.

big-vee-twin - 16/7/13 at 01:02 PM

Duratec

big_wasa - 16/7/13 at 03:24 PM

Yep tuning anything Na is a money pit but I would agree with the st170 lump.
Many of the bits you have on the zetec will swap over. The inlet ports are 10mm higher and you will want to go upto a 2.5" exhaust to let it breath.

What gives the St lump more power is the better breathing with more compression, better internals are a bonus. All of this can be done to a zetec with the same results but you cant do it for the price of used St170 engine.

MikeRJ - 16/7/13 at 03:51 PM

quote:
Originally posted by ianm67
Would it not be simpler / cheaper to change you diff to a 3.6? This would give you a higher top speed before you hit the limiter in 4th...?


Far better to go for a higher ratio (e.g. 4.27:1) so that 5th becomes a usable gear and all the gears effectively become closer.

richardm6994 - 16/7/13 at 04:06 PM

quote:
Originally posted by MikeRJ
quote:
Originally posted by ianm67
Would it not be simpler / cheaper to change you diff to a 3.6? This would give you a higher top speed before you hit the limiter in 4th...?


Far better to go for a higher ratio (e.g. 4.27:1) so that 5th becomes a usable gear and all the gears effectively become closer.


I was thinking that! Better acceleration for the same powered engine and also you'll be using all 5 gears.

I also agree with the other comment earlier about being better off spending your money on a engine that has the power you want to begin with rather than tuning a lower spec engine.

With NA engines, you can spend a fortune (in relative terms) for very little bhp gains and at the end of it all you end up with an unreliable engine because it's running on or close to it's limit.

ianm67 - 16/7/13 at 04:08 PM

quote:
Originally posted by MikeRJ
quote:
Originally posted by ianm67
Would it not be simpler / cheaper to change you diff to a 3.6? This would give you a higher top speed before you hit the limiter in 4th...?


Far better to go for a higher ratio (e.g. 4.27:1) so that 5th becomes a usable gear and all the gears effectively become closer.


Surely that's a lower ratio? The ratios won't become closer, they'll just be lower..? That diff was only avaiable in the Scorpio and is the lobro type. Good luck finding one......

baz-R - 16/7/13 at 04:31 PM

there are meny tales of 2.0l cams been of a very simular profile to rs1800 ones this is not true. you only have to look at what peak power and torque rpm's each engine makes

a simple way to make better power is to fit proper cams or mabe try and retime the 2.0l ones to get full lift at 110deg btdc and atdc and see if that gives you see a few free bhp

if your putting new cams in make sure you pick one that is ok for piston/valve clearance!

fit uprated big end bolts if you plan on going up into the 7k rpms, hydro lifters are going to be ok unless your going wild on the cam profiles but all i looked at need valve cut outs in pistons as lift at tdc are too high.

will121 - 16/7/13 at 08:18 PM

quote:
Originally posted by ianm67]

Not as simple as that I'm afraid...... The silvertop engine uses hydraulic cam followers which restricts maximum RPM. The Blacktop uses solid cam followers hence the higher maximum RPM.
A set of cams from someone like Newman or CatCams might give you another 5-6 bhp but will cost you £400 so not the best return on your investment.....
Bear in mind that your engine was once pulling around a Focus or Mondeo. In your car (550kg?) the 1.8 shouldn't have any problem coping with a slighty higher diff ratio. A diff swap would be my first port of call.......


My silvertop makes peak at 7k and not had a issue with cam followers.
1.8 may not be best starting point over a 2litre zetec but should get a reasonable return with cams and a DIY ported head which will aid breathing and possibly peak power, but may reduce mid range.
Don't believe 7s are really about top speed and not necessarily most airodynamic, handling and acceleration bonus

DavidW - 16/7/13 at 08:29 PM

I can see both sides of the diff ratio question but figure if I'm looking for higher speeds on a fixed distance, I need acceleration, so logically a higher diff.

If I was flying through the rev range in 4th I'd go for the lower diff but I don't think I have the power to do that.

So....

St170 seems a great budget option but gets more expensive if to get the power I need to change to a 2.5" exhaust and have my custom alloy intake manifold altered?

Maybe I need to look for modest gains with a normal zetec which I think means cams?

teegray19 - 16/7/13 at 10:11 PM

Why not go bike engine? 150-165bhp for less than 200quid in many cases... loose all the weight gain more power.

That's what I'm doing over winter.

austin man - 16/7/13 at 10:41 PM

I swapped diffe went from a 3.6 to a 3.9, 1.8 zetec on TBS and lost 15mph I will be changing the diff back. There will be a drop in initial acceleartion however first gear is pretty much useless so you are through the box rapidly on both diffs

mccsp - 16/7/13 at 10:43 PM

I don't think aftermarket cams are the way forward. My 2l Zetec makes 169bhp running the 130cams. I have an emerald ecu, gsxr 750tb's, home ported head, skimmed head (slightly higher compression) and 4 into 1 exhaust, not convinced it is a great manifold as unequal lengths and the runners are very long. When it was being mapped losing the airbox would have gained another 4bhp, but don't think it is a wise route! Having mapped it and run it through gt power at work, there was negligible benefit from any of the standard aftermarket cams, that didn't require piston pockets cutting!

I have a 3.92 diff, and have been pretty happy with the performance, tips out around 115/120 depending on how accurate the speedo really is! Drag on a 7 is massive! I have a windscreen fitted. I would think about cheap ways to reduce drag.

Corner exit speed will also play a big part, if acceleration is the problem.

will121 - 17/7/13 at 06:23 AM

quote:
Originally posted by mccsp
I don't think aftermarket cams are the way forward. My 2l Zetec makes 169bhp running the 130cams. I have an emerald ecu, gsxr 750tb's, home ported head, skimmed head (slightly higher compression) and 4 into 1 exhaust, not convinced it is a great manifold as unequal lengths and the runners are very long. When it was being mapped losing the airbox would have gained another 4bhp, but don't think it is a wise route! Having mapped it and run it through gt power at work, there was negligible benefit from any of the standard aftermarket cams, that didn't require piston pockets cutting!.


I have basically the exact same setup but with 260 newman cams and as you say mine only makes 4bhp more at 173bhp when mapped at emerald but does make this peak power at 7000rpm. Do you have your RR print out? I will add mine tonight, be interesting what if any the advantage of cams actually are.




[Edited on 17/7/13 by will121]

FASTdan - 17/7/13 at 01:45 PM

quote:
Originally posted by teegray19
Why not go bike engine? 150-165bhp for less than 200quid in many cases... loose all the weight gain more power.

That's what I'm doing over winter.


£200 to go CEC - > BEC?

teegray19 - 17/7/13 at 05:36 PM

ZZR1100 package off someone on here for £200 and got given a prop that fits lovely. After the MOT it's going in and be enjoying 12k rpm. It's the future!