Engine mods to a carbed turbo
Discussion
I was just talking to my lotus mechanic yesterday and agreed it would be nice to have two esprits, one for concourse shows and the other kept aside for the track. He was saying you can get over 400hp out of the four cylinders like mine with serious mods, I never really asked him what these mods were as I was too interested in sitting in the new V8's 
. I searched here from an old post by Jim (lotusguy) which said.......
There are several good mods you can do to the carb'd turbos, including adding a BOV. Just a few mods I made to my carb'd turbo:
1. Advanced the valve timing 6° to restore the original engine spec. by swapping the 110 intake cam pulley for a 104 intake cam pulley
***What benefit does this do?
2. Added a slightly more agressive 104 cam (0.412" lift vs. 0.378" stock).
3. Re-jetted the carbs. How much more HP does this produce?
4. Re-curved Distributor to bring on all 16° of advance at 2,100 RPM
??
5. Recalibrated the wastegate to produce 10.0PSI of boost vs. the stock 7.5PSI.
Can I just get a bigger turbo installed?
6. Ceramic coated the exhaust header and assoc. parts for lessened turbo lag and better heat management.
7. Added SS Clutch and Brake Hoses
8. Added custom made adjustable upper rear links - (the pre-S4 cars had fixed links).
Any other ideas?
. I searched here from an old post by Jim (lotusguy) which said....... There are several good mods you can do to the carb'd turbos, including adding a BOV. Just a few mods I made to my carb'd turbo:
1. Advanced the valve timing 6° to restore the original engine spec. by swapping the 110 intake cam pulley for a 104 intake cam pulley
***What benefit does this do?
2. Added a slightly more agressive 104 cam (0.412" lift vs. 0.378" stock).
3. Re-jetted the carbs. How much more HP does this produce?
4. Re-curved Distributor to bring on all 16° of advance at 2,100 RPM
??
5. Recalibrated the wastegate to produce 10.0PSI of boost vs. the stock 7.5PSI.
Can I just get a bigger turbo installed?
6. Ceramic coated the exhaust header and assoc. parts for lessened turbo lag and better heat management.
7. Added SS Clutch and Brake Hoses
8. Added custom made adjustable upper rear links - (the pre-S4 cars had fixed links).
Any other ideas?
Yes, you can get real deal power with some serious mods (I wonder how much I'm getting these days???)
However, the tranny will still always be the limiter. You'll burn the clutch out over 350HP pretty fast, unless you go with a beefier option. And your 2nd gear synchros will always suck no matter what you do.
The V-8s, even with their beefier clutches, don't come close to their incredible amount of potential. That engine can be pushed to 650, and beyond, but the POS tranny can't even begin to stand up to such punishment. It's a shame, too. 450 is about as high as I'd go with one of them unless I had the 20 grand or so for a Quafe or Hewland tranny.
Mike
PS - read up on my mods page...alot done there, and tho I don't have the dyno slips (yet) the car is ridiculously fast.
However, the tranny will still always be the limiter. You'll burn the clutch out over 350HP pretty fast, unless you go with a beefier option. And your 2nd gear synchros will always suck no matter what you do.
The V-8s, even with their beefier clutches, don't come close to their incredible amount of potential. That engine can be pushed to 650, and beyond, but the POS tranny can't even begin to stand up to such punishment. It's a shame, too. 450 is about as high as I'd go with one of them unless I had the 20 grand or so for a Quafe or Hewland tranny.
Mike
PS - read up on my mods page...alot done there, and tho I don't have the dyno slips (yet) the car is ridiculously fast.
You can always add water injection and a race actuator. WI to cool the combustion temperature down and the actuator to increase boost to 0.85-0.9BAR. Cooler plugs, your could go next temperature range up or try Iridiums. I tried Densos but they soon clogged up. May try out the NGK's. Iam running standard NGK's but the next temperature range up.
Dave Walters
Dave Walters
The earlier carb cars did not have forged pistons, so are not too forgiving when given increased boost, also the Citroen tranny, clutch, etc. is weaker than the Renault set-up. The front suspension on pre '84 is pretty basic, not the best for track.
If you want to get the most enjoyment out of tracking an Esprit, I would suggest a Stevens model with the GM injection, outboard brakes, and Renault tranny. It will cost a bit to get any car set up for track, with the later model there is more room for future mods but with the earlier cars you will have invested money in something that has finite capabilities.
Steve
If you want to get the most enjoyment out of tracking an Esprit, I would suggest a Stevens model with the GM injection, outboard brakes, and Renault tranny. It will cost a bit to get any car set up for track, with the later model there is more room for future mods but with the earlier cars you will have invested money in something that has finite capabilities.
Steve
If you are buying a track car then the cheapest method of cooling is an intercooler from any turbo diesel car froma breakers. You can retro fit this under your boot floor and cut away as necessary. Obviously your road car, you can't do that as you don't have enough room.
I was toying around with trying out an intercooler but the length of pipe even to the rear bumper would creat a lot of turbo lag.
I was toying around with trying out an intercooler but the length of pipe even to the rear bumper would creat a lot of turbo lag.
I have one of the last Giugiaro HC Turbos, which has the same carbed motor as the early Stevens cars.
I'd be interested to hear about simple mods that can be done to cams, cam timing, ignition, inlet, boost pressure etc...
In other words, what can be done without lifting the motor out.
Cheers
Pat
I'd be interested to hear about simple mods that can be done to cams, cam timing, ignition, inlet, boost pressure etc...
In other words, what can be done without lifting the motor out.
Cheers
Pat
PatHeald said:
I have one of the last Giugiaro HC Turbos, which has the same carbed motor as the early Stevens cars.
I'd be interested to hear about simple mods that can be done to cams, cam timing, ignition, inlet, boost pressure etc...
In other words, what can be done without lifting the motor out.
Cheers
Pat
Kylie, Pat et al,
Hi,
There are a variety of mods which can be made to an early 'G' car which will boost the HP considerably. It all depends on the amount of time, cash and work you're willing to invest.
At the Unlimited end of the spectrum, Forged, lightened ConRods and Pistons (w/ lower profile), Radical Cam, Forged Steel Bucket Tappets, Ported and Polished Intake Manifold, Non-Venting Dump Valve, Water-injection, re-jetted Carbs, conversion to Dry Sump oiling system, Zero-Balancing, Re-calibrated Wastegate, Engine Management system such as Electromotive's Tec-1, are some of the things you'll want on the list. This will allow the engine to spin close to 9,000RPM. Very spendy as a whole, but guaranteed to free up a whole lot more ponys.
To direct those ponys to the rear wheels, you can get a lightened Flywheel, Multi-plate Clutch, add a tranny cooler and beef up the CV joints. To reign them in, you can go multi-pot calipers w/ brake ducting and water-injection system for the brakes. Since you are now approaching P*rsche GT-1 money, we'll assume this is too rich for your tastes.
A more sensible approach would be to advance the engine timing, advance ignition timing to 28°, Re-curve distributor to add-in all advance by 2300RPM, do a Valve Job, add a slightly more radical (higher Lift) Cam such as a 104 Cam or a DS2 Cam, Forged Pistons, Recalibrated Wastegate, Ported and Polished Intake Manifold, Recalibrated Wastegate to 10PSI, Re-jetted carbs, Zero-Balancing. All this can be done for under $2,500 and will add 30-50HP while still leaving the car some street manners. I did all these things to my '85MY Turbo except for the Porting and Polishing, which I now wished I had done. Still, it will run with the SE's and if one's SE isn't in top form, all they're gonna see is my tail lights. Hope this helps...Happy Motoring!...Jim'85TE
th4neuk said:
Which car are you using for the track BTW. Your current Black Beauty or are you getting another one????
Along with what Dave has put you could also retro fit a chargecooler. This would bring down intake temps.
Cheers
Alan Croft
Hi Alan, sorry for delay in reply been out boating for the weekend, I was refering to my black 89 non se. I would eventually like a later model V8 for concourse shows and keep the black one for fun club events so I can pop it on a trailer and not too worried if something breaks down. Not planning on bending it, I just want a car that I don't feel guilty giving it a real push if you know what I mean. To bring my car back to original condition for shows etc would take a lot of work and I like the look of my car far better than when it was stock. So I am not too worried about altering the orignal engine with a few mods.
lotusguy said:
A more sensible approach would be to advance the engine timing, advance ignition timing to 28°, Re-curve distributor to add-in all advance by 2300RPM, do a Valve Job, add a slightly more radical (higher Lift) Cam such as a 104 Cam or a DS2 Cam, Forged Pistons, Recalibrated Wastegate, Ported and Polished Intake Manifold, Recalibrated Wastegate to 10PSI, Re-jetted carbs, Zero-Balancing. All this can be done for under $2,500 and will add 30-50HP while still leaving the car some street manners. I did all these things to my '85MY Turbo except for the Porting and Polishing, which I now wished I had done. Still, it will run with the SE's and if one's SE isn't in top form, all they're gonna see is my tail lights. Hope this helps...Happy Motoring!...Jim'85TE
I took an interested in this and was considering engine tweaks last year but in the end decided to first get the breaks upgraded which also required bigger wheels etc. Thats now been done so once again I'm looking into this for autum project.
I have already checked and found I do have 104 Green Dot pully installed (being a Euro car). Jim you mention a DS2 cam. Is thats better than a 104 cam or just an alternative. If it a better cam where can I get one in the UK. I already have a well know contact (Esprit Engineering) in the UK who can polish the head to around 170cfm and so it makes sense to have the new cam fitted at that time.
On this subject is there and difference in a 91SE head? One is for sale at the mo and would consider getting that head to be done so I would not have to take my car off the road.
The mention of forged piston was made. Can someone confirm that an 89 turbo should have these already? Again a set of nearly new HC pistons are for sale, would these be suitable and forged (if needed).
The wastegate I was going to fit a beed valve so I can adjust it from stock only when necessary. Anyone recomend a part and supplier for this?
Rejetting the carbs. What size jet do you recommend going to. Last time I looked I think you can get them going up in .2 increments but have to confess to not know what it is now or whats best to go for.
Now for something that I hadnt come across before, 'Re-curve distributor'. What exactly does this involve?
Sorry for the barrage of questions but I'm not a mechanic but a fast learner and willing to give anything a go. However that does not mean I like to go in blind.
Should also add that I already have a new CC and are likely to use the aircon rad to fit this. Any problems in simply removing the pump/compressor (whatever it is).
Steve
89 Turbo
www.unity1.co.uk/Lotus
Steve,
Don't get confused between a 104° Pulley and a 104 Cam. The 104 Pulley sets the valves MOP (Maximum Opening Point) at 104° of crank rotation whereas the 104 Cam is merely a moniker for a cam which has certain characteristics (0.412" lift, 272° duration). It is a higher lift cam than the stock cam. In other words, one is responsible for cam timing, the other for valve lift etc.
The DS2 Cam is a higher lift cam yet and is considered a mild race or radical street cam. I know a couple people who run them on the street w/ no problems, although their idle isn't as smooth and they are most likely a little more bottom end challenged. It was developed by famed Lotus engine tuner Dave Smith
hence the DS nameake. Nigel @ London Lotus Center can probably steer you in the right direction here.
As far as your shop is concerned, porting over polishing for maximum benefit. There is no difference in the heads you describe, and yes, you already have the HC liners and matched forged pistons (these are sold as matched sets only).
Can't help you with a bleed valve source ...sorry.
Rejetting carbs is best done on a dyno once all the cam and timing work is done, anything less is pretty much guessing. And you need to know what you already have as a starting point. Really fine tuning can be a combination of jets and corrector tube changes. Use Matthew Cooper at Eurocarb LTD (<a href="http://www.dellorto.co.uk">www.dellorto.co.uk</a>
as a resource for both parts and advise.
Recurving the distributor is a matter of swapping weights and springs on the distributor's internal advance plate to make the distributor advance at a different RPM. It is spun up on a dedicated machine which shows the advance curve of the dist. It is also used to monitor the effects of different weights and springs until the desired advance is achieved. Here in the States, we also have vacuum advance on our distributors mostly for emissions, something I understand you all don't have. But, getting all the advance to come in just off idle and at the point where the transition to the Main carb circuits is achieved, allows you to maximize the rest of the RPM scale.
No problem disconnecting or removing the A/C compressor. Just be aware that you'll lose some refrigerant (may be environmental rules governing this) and some oil. Pull the appropriate fuse for the comp. so you don't have any associated electrical problems.
No worries for the questions. Keep 'em coming if I can help. Happy Motoring! ...Jim'85te
>> Edited by lotusguy on Saturday 26th June 12:39
Don't get confused between a 104° Pulley and a 104 Cam. The 104 Pulley sets the valves MOP (Maximum Opening Point) at 104° of crank rotation whereas the 104 Cam is merely a moniker for a cam which has certain characteristics (0.412" lift, 272° duration). It is a higher lift cam than the stock cam. In other words, one is responsible for cam timing, the other for valve lift etc.
The DS2 Cam is a higher lift cam yet and is considered a mild race or radical street cam. I know a couple people who run them on the street w/ no problems, although their idle isn't as smooth and they are most likely a little more bottom end challenged. It was developed by famed Lotus engine tuner Dave Smith
hence the DS nameake. Nigel @ London Lotus Center can probably steer you in the right direction here.
As far as your shop is concerned, porting over polishing for maximum benefit. There is no difference in the heads you describe, and yes, you already have the HC liners and matched forged pistons (these are sold as matched sets only).
Can't help you with a bleed valve source ...sorry.
Rejetting carbs is best done on a dyno once all the cam and timing work is done, anything less is pretty much guessing. And you need to know what you already have as a starting point. Really fine tuning can be a combination of jets and corrector tube changes. Use Matthew Cooper at Eurocarb LTD (<a href="http://www.dellorto.co.uk">www.dellorto.co.uk</a>
as a resource for both parts and advise. Recurving the distributor is a matter of swapping weights and springs on the distributor's internal advance plate to make the distributor advance at a different RPM. It is spun up on a dedicated machine which shows the advance curve of the dist. It is also used to monitor the effects of different weights and springs until the desired advance is achieved. Here in the States, we also have vacuum advance on our distributors mostly for emissions, something I understand you all don't have. But, getting all the advance to come in just off idle and at the point where the transition to the Main carb circuits is achieved, allows you to maximize the rest of the RPM scale.
No problem disconnecting or removing the A/C compressor. Just be aware that you'll lose some refrigerant (may be environmental rules governing this) and some oil. Pull the appropriate fuse for the comp. so you don't have any associated electrical problems.
No worries for the questions. Keep 'em coming if I can help. Happy Motoring! ...Jim'85te
>> Edited by lotusguy on Saturday 26th June 12:39
Dave Smith hasn't been tuning Lotus engines for about 15 years now, although he still does gas flowed heads from home. I'm surprised to see DS2's still mentioned as it's a long time since he's been selling cams or builoding engines: the DS2 was actually a Kent L14 which is a 283 degree grind with 0.420 lift - The 104 would be better for a turbo car as it has the same lift, with a steeper ramp angle, keeping the total duration to 272 degrees, which will help keep the car tractable at lower rpms.
Watership Down said:
I have an 87 Turbo HCI with a chargecooler fitted. Do the same modifications apply to my car as the carbed models or are there slightly different mods. I live in Canada
>> Edited by Watership Down on Saturday 26th June 15:52
Hi,
Your car would benefit from the same distributor and cam/pulley mods. Obviously, the carb info is moot. Happy Motoring! ...Jim'85TE
grk said:
Dave Smith hasn't been tuning Lotus engines for about 15 years now, although he still does gas flowed heads from home. I'm surprised to see DS2's still mentioned as it's a long time since he's been selling cams or builoding engines: the DS2 was actually a Kent L14 which is a 283 degree grind with 0.420 lift - The 104 would be better for a turbo car as it has the same lift, with a steeper ramp angle, keeping the total duration to 272 degrees, which will help keep the car tractable at lower rpms.
Hi,
The DS2 cam is still a very good profile to run although I agree that the N/A cars realize more benefit in doing so. I am running the 104 Cam in my carb'd '85 Turbo primarily to preserve the low end performance and good idle. I've had it for 2 years and 10k mi. and think it's a positive upgrade, although you do feel the slight loss of bottom end. Since I don't drag or standing start, I really don't miss it at all, but love the bolstering of the power curve in the tach's upper regions.
The DS2 Grind is still available, although perhaps not directly from Dave Smith and is a slightly more agressive alternative to the 104. Happy Motoring! ...Jim'85TE
Gassing Station | Esprit | Top of Page | What's New | My Stuff