Lotus Elan Central

by **Houdini** » Tue 25.10.2005, 19:52

More Turbos being looked at. I have started looking deeper into the Turbo selection process and may have found the best compromise. In total I looked at 5 different Turbos and one seems to fit the bill the best for packaging and power. It's the GT2560R which is good for between 200-280 HP and looks real good in the 265-270 Hp range which should be good enough (downgrading my 300-320 HP ambitions for better response). Best of all it will bolt up to my adapter and the compressor will point down like the stock setup out of the box, making that part of the plumbing easy. The turnine housing is Ni resist, the turbine wheel is Inconnel, turbine trim is 60 and A/R is .64, compressor trim is 62 and A/R is .60. Problem is I don't have a Turbo to test fit and I'm going off the drawings which is good enough. A Turbo is on order for me to test fit and as soon as I have it I'll take pictures. I can still go ahead with the downpipe though as the turbine housing configuration is the same and won't change between any GT25 or GT28 frame size.

,Russ

by **Doc Fizzix** » Wed 26.10.2005, 01:43

Russ, I met with my engine builder today and he asked me if we were going to raise the compression a little on my rebuild. I told him that I had always been told not to raise the compression on a turbo engine when rebuilding. He told me that he likes to bump the compression up a small amount to help give the engine a little more power to overcome any turbo lag.

Here is my question to you, what is the correct answer, can you bump the compression up a little to give your motor a little more to overcome any turbo lag?

by **Houdini** » Wed 26.10.2005, 04:54

I PM'd you.

by **Dave M** » Wed 26.10.2005, 13:54

LotusM100 wrote:Here is my question to you, what is the correct answer, can you bump the compression up a little to give your motor a little more to overcome any turbo lag?

FWIW, my engine guy said to stick with the stock compression. In my mind it allows flexibility for a variety of boost levels and octane ratings - just in case you live in CA!

by **Doc Fizzix** » Wed 26.10.2005, 15:06

You guys are great! Thanks for your input and help on this :wink:

by **Costas** » Wed 26.10.2005, 20:57

I, on the contrary, lowered compression ratio. The stock engine gusget is of 1.4 mm thickness while the handmade one I installed is of 3.1 mm thickness so as to drop combustion (compression ?) ratio.

Costas

by **Doc Fizzix** » Wed 26.10.2005, 21:21

It would be nice to read up on this, anyone have some good links a fellow could read?

by **Monty** » Wed 26.10.2005, 23:17

Turbocharger wrote:More Turbos being looked at. I have started looking deeper into the Turbo selection process and may have found the best compromise. In total I looked at 5 different Turbos and one seems to fit the bill the best for packaging and power. It's the GT2560R which is good for between 200-280 HP and looks real good in the 265-270 Hp range which should be good enough (downgrading my 300-320 HP ambitions for better response). Best of all it will bolt up to my adapter and the compressor will point down like the stock setup out of the box, making that part of the plumbing easy. The turnine housing is Ni resist, the turbine wheel is Inconnel, turbine trim is 60 and A/R is .64, compressor trim is 62 and A/R is .60. Problem is I don't have a Turbo to test fit and I'm going off the drawings which is good enough. A Turbo is on order for me to test fit and as soon as I have it I'll take pictures. I can still go ahead with the downpipe though as the turbine housing configuration is the same and won't change between any GT25 or GT28 frame size.

,Russ

This is sounding good, but worried the cost could get ou of hand with all the other bits required. Since i`ve never been down this route of upgrades could u give us a quick list of the other aftermarket componets were going to need ie injectors, ECU etc and what be a rough price and a package like this?

by **F1 LOTUS** » Thu 27.10.2005, 07:44

I would be interested in a turbo that gives significantly less lag AND a bit more power than stock (stock can achieve 220-230BHP?), yet retains the original ECU

by **Nige** » Thu 27.10.2005, 12:00

I think that probably sums up where most of us would want to be Brian. as it keeps it just below the point where costs really begin to spiral and should also be very driveable.

by **Costas** » Thu 27.10.2005, 15:02

Agreed, but..... a turbo with more power yet less lag is kinda hard to do without beeing costy... Perhaps sacrifise lag for power or vice versa.

by **Houdini** » Thu 27.10.2005, 16:24

Brian,

(stock can achieve 220-230BHP

I plan on taking the stock Turbo apart in the next couple of weeks to get a feel for the A/R, trim, etc. A quick look at the turbo makes me think it's close to our GT15 or GT20 series Turbos which would make it good for 200-220 HP maybe. I wouldn't use one of those since they're a journal bearing turbo I don't see any advantage for the hassle of making it work over the stock. I also think that 220-230 out of the stock Turbo maybe stretch unless it's for very short bursts. It looks like a turbo that is most comfortable at maybe 180 or so.

by **Costas** » Thu 27.10.2005, 16:46

Turbocharger wrote:
(stock can achieve 220-230BHP

I Dynoed 237hp with the stock IHI Turbo at 1.05 steady boost pressure and had 28kgm of torgue (or is it torque?)
I also did a dyno the day before that (with no racing exhaust-downpipe-cat) and Dynoed 220hp.

But at that daily constant operating limit the stock Turbo didnt last long enough, after less than a year it needed a full rebuild.

So there you go about the stock Turbo, through my very own experience!

Costas

by **F1 LOTUS** » Thu 27.10.2005, 18:47

My stock BHP comment was based upon LEC reports not personal experience.
Less lag and more power...I'm speculating that the +15 years of potential development time elapsed since our IHI unit was designed would enable us to achieve both

...

by **Dave M** » Thu 27.10.2005, 19:11

Brian_MDB wrote:My stock BHP comment was based upon LEC reports not personal experience.
Less lag and more power...I'm speculating that the +15 years of potential development time elapsed since our IHI unit was designed would enable us to achieve both ...

Russ can confirm, but I'm guessing any of the smaller Garrett GT-series turbos should be able to do this for our engine.

by **Houdini** » Thu 27.10.2005, 20:01

Brian,

It's all good, I know your comment was based on the LEC comments.

All,

I did some calculations based on some assumtions about our engine and the capability of the charge cooler and came up with 195 HP at .92 bar pressure. I then ran the calcs assuming 220 HP and came up with 1.15 bar as the required pressure which is pretty darn close to Costas 1.05 bar so by changing a couple of numbers it's close enough.

Our smallest ball bearing turbo the GT2554R shows a 170-250 HP range for 1.4-2.2 liter engines. This looks like a turbo that would work very nice at around 225 Hp for our engine without spending money on the intake, head, and exhaust manifold. You would prabably have to run 1.15-1.2 bar (16.6-17.3 psi) to achieve this.

All of the turbos smaller than this are journal bearing right now and unless there is demand for smaller ball bearing turbos (which there probably will be) the one mentioned above is the best bet.

Orientation wise the GT2560R is the best, and with appropriate modifications will give you 250-280 no problem. I've been told, but it hasn't been verified that this turbo can give up to 310 hp, but I feel this is out of the 1.6 liter range without going to a bigger (more lag) turbo.

by **Costas** » Thu 27.10.2005, 20:30

That is Great Feedback! You ppl have so thorough knowledge of the subject that you make me envy you

Keep the data and info coming!

Costas

PS. Brian, I know you posted based on Lec data

My post was to verify you actually, hope I wasnt missunderstood. :cry:

by **Houdini** » Tue 01.11.2005, 04:12

Well here are 3 pictures of the GT2560R bolted in place. Positive things to note are that it clears everything. The compressor discharge is pointing down and the connection to the charge cooler is now a piece of cake. The last thing to note is that this could turn out to be an extremely stealth installation as the last picture shows with the heat shield fitting over the turbine housing. It is a tight fit but I think it will work. Of course anybody that knows the car will see that it's not the stock turbo, but I think it will look very close to stock except for the larger housing. Check it out for yourself.

by **Monty** » Tue 01.11.2005, 12:37

WoW

thats more like it

i can see project creep starting again :roll:

What about a rough price on this turbo unit? so i can start saving my pennies

Keep up the good work Russ

by **Matt RI** » Tue 01.11.2005, 16:52

Boy am I glad that I had my fingers crossed when I promised the wife I would take it easy on further modifications to increase horsepower... I am getting a little antsy now, Russ!

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