Car wont hold boost

[allan-lambo]

Hey guys, i have a 2003 1/2 Esprit, which i dynoed at 344 rwhp bone stock. Next we added Johans ECU upgrade which brought the hp up to 350rwhp, but shot torque up by 39ft pds to 339ft pds. Next we did full exhaust, no cats, and added a boost control set at 1 bar, and blow off valves. We dynoed again at 359rwhp, and torque went down to 324ft pds. Being rather dissapointed in these numbers, we narrowed it down to the wastegate capsules not being able to keep the boost. Anyone have good places to get a set which will hold 1 bar cheaply?

Enclosed is a pic of my Esprit.

[EspritFactFile]

Allan,

I remember after you bought your car and posted your initial stock HP and torque figures that Dan Adragna and I wondered if you would be disappointed with your Johan ECU upgrade.

Since your car is a 2003.5MY, it already had a significant jump in performance over prior V8s. Not only because it was supposed to be a High-Torque ECU, but it seems obvious to us now that Lotus added some extra HP as well.

Our suspiscion is that Johan's chip normally feels like a huge improvement because they are upgrading older V8s that don't have hi-torque as stock. However, on your car, it wouldn't be such a huge improvement and could, in fact, be a little worse.

[allan-lambo]

Allan,

I remember after you bought your car and posted your initial stock HP and torque figures that Dan Adragna and I wondered if you would be disappointed with your Johan ECU upgrade.

Since your car is a 2003.5MY, it already had a significant jump in performance over prior V8s. Not only because it was supposed to be a High-Torque ECU, but it seems obvious to us now that Lotus added some extra HP as well.

Our suspiscion is that Johan's chip normally feels like a huge improvement because they are upgrading older V8s that don't have hi-torque as stock. However, on your car, it wouldn't be such a huge improvement and could, in fact, be a little worse.

<{POST_SNAPBACK}>

Its not Johans chip that im dissapointed in. His chip made 6 rwhp, but added almost 40 rear ft pds of torque! I was very happy with that. What dissapointed me is that we went to full exhaust, and turned the boost up, and it only made 9rwhp more, and torque went down. This is obviously due to the fact that the car is not holding boost.

[lotusracing]

Greetings,

If you remove the boost controller your HP and torque will go back up.

The boost controller is fighting the ECU. You have more boost and less power.

The ECU is detunning th eengine by retarding the timming and cutting fuel.

The capules are not the primary problem here.

-Larry

Finesse Over Power

Hey guys, i have a 2003 1/2 Esprit, which i dynoed at 344 rwhp bone stock. Next we added Johans ECU upgrade which brought the hp up to 350rwhp, but shot torque up by 39ft pds to 339ft pds. Next we did full exhaust, no cats, and added a boost control set at 1 bar, and blow off valves. We dynoed again at 359rwhp, and torque went down to 324ft pds. Being rather dissapointed in these numbers, we narrowed it down to the wastegate capsules not being able to keep the boost. Anyone have good places to get a set which will hold 1 bar cheaply?

Enclosed is a pic of my Esprit.

<{POST_SNAPBACK}>

[allan-lambo]

Greetings,

If you remove the boost controller your HP and torque will go back up.

The boost controller is fighting the ECU. You have  more boost and less power.

The ECU is detunning th eengine by retarding the timming and cutting fuel.

The capules are not the primary problem here.

-Larry

Finesse Over Power

<{POST_SNAPBACK}>

But i thought that Johans ECU was designed to work with additional boost? I have emailed Johan to get his response.

[scoule]

But i thought that Johans ECU was designed to work with additional boost? I have emailed Johan to get his response.

<{POST_SNAPBACK}>

I thought the ECU manages the boost for you .. bleeding away from the wastegate capsules to give up to 1 bar as temperature and conditions permit?

Perhaps if the external boost controller is allowing more boost than Johans ECU thinks is safe, it is backing off to save the engine?

[allan-lambo]

I thought the ECU manages the boost for you .. bleeding away from the wastegate capsules to give up to 1 bar as temperature and conditions permit?

Perhaps if the external boost controller is allowing more boost than Johans ECU thinks is safe, it is backing off to save the engine?

<{POST_SNAPBACK}>

Working on getting new capsules, that will hold boost.

[lotusracing]

The ECU is NOT designed for a external boost controller. The Code tries to maintain 11psi boost max.

BTW I have the source code of the ECU, and am the original source of the code to Johan.....

-Larry

[senna21]

You're ECU may be pulling the timing back because it's reading KNOCK. If it is you'd better be careful.

Here's the way our ECUs (Toyota MR2 Turbo) work in these situations and I'm guessing most will act accordingly.

When you up your boost you're increasing the amount of air and fuel in the combustion chamber (I know you already know that). When you do so the charged air/fuel mixture goes into the chamber at a much higher temperature than at a lower boost. That higher temp air/fuel has a greater tendency to predetonate (knock). That's why if you're going to up your boost you should also be looking at some upgrade to cool your intake charge better. Boost usually doesn't kill engines... side effects of boost does. Specifically knock. Knock is what will lead to burning a hole in your piston, valve or killing piston rings.

Because of this when the ECU reads knock (from your knock sensor- I can't imagine this engine doesn't have one) it'll pull the timing and also probably dump more fuel into the combustion chamber than normal in order to cool the combustion chamber down. Lean Air/fuel mixture will cause combustion temps to rise, and rich Air/fuel mixture will cause it to cool down. With the timing pulled and more fuel you'r going to get less HP and torque.

No where in your list of mods have I seen any kind of intercooler upgrade. I'd say that's your next line of attack. You'll gain HP and reliability. If not I'd say you're heading for an engine rebuild somewhere in the not too distant future.

[TEAM MAG]

I went through this whole process with my 2002 which had the high torque ECU upgrade. I Purchased a VDO boost gauge, ran it with the stock set-up and saw about 8-9psi boost. Then purchased Johan's chip and found basically the same numbers except the boost limit control is removed from all gears...making the car feel faster. I tested the capsules, lines etc... and found all in working order (the car has 2k miles). I purchased a new frequency valve from Lotus and found no difference. I assumed that Johan's chip would give more boost. I then removed the CATS and saw up to 10 psi with better throttle response. Looking for more boost, I have now purchased a Turbo-X manual boost controller. I am now seeing about 11-13 psi with about 5 turns on the controller. I really don't feel that much difference however. The car still hauls ass but I would think with 3 more psi it would feel even faster. Could the ECU be limiting things? I might just head down to the Dyno and test the effects of this boost controller. FYI- Turbo Engineering can make up some capsules for the V8- 303-271-3997.

[lotusracing]

Greetings,

NONE OF THE ECU's except for the GT1 version increase the boost.

If you increase the boost eh ECU will fight it.

The other versions of the ECU do increase the torque some and allow higher boost sooner in lower gears.

If you are using the car on the track the highest sustainable boost is around 8psi.

Since I rebuild these engines and transmissions form people who dont get this yet....

Keep increasing the boost until A.. You believe...

or B... You run out of money from having your car broken...

In any case Enjoy

-Larry

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1998 Esprit 650 Hp GT1 race car

1998 Esprit