V 8 engine temp in traffic

[Mr JP]

What is a normal engine temp for a V8 to run at?

Mine runs at about 85 deg C when on a clear road at speed but gets as high as 100 deg C in traffic.

The temp in traffic seems a bit high to me, I’ve even seen it at just over 100 deg C. Is that normal? Would better quality fans and / or a high capacity radiator be worth thinking about?

JP

[ErnestM]

Better fans, better radiator would help. Kmaier on here seems to be the resident expert on this, perhaps he will comment.

I have found good results just adding water wetter to the coolant.

ErnestM

[feffman]

John:

The stock radiator is right at the limit on the V8. If it's slightly clogged internally of blocked with debris externally it will run warm. The radiator has only two rows in the stock core. Your temps are pretty normal.

Last fall I pulled my radiator due to a leak and found the core was about 30% clogged (even after annual flushings). I took the radiator to a reputable repair shop and had them re-core it with a heavy duty core that has two extra rows (for a total of four rows in the core). It now rarely goes above 92 degrees in hot weather even with the AC on. I kept the stock fans per a Lotus Cars USA tech. My cost around US $500. Probably some of the best "peace of mind" money I've spent on my Esprit.

Mark "Feff" Pfeffer

[Mr JP]

Thanks for that info. It’s good to know that the temps are normal but it does seem that it might be a very good plan to look into getting a bit more cooling capacity.

[deecee]

Try RC 20...it is a water additive that we use it for racing and it really works.

[Mr JP]

Deecee - I'll give that a go!

Thanks - JP

[toyroom]

Colin Chapman was quoted as saying: "It's up to the engineers to tell the customer whatever they like with the temperature guage but the engine in a Lotus should run as close to 100 degrees as possible !" Who are we mere mortals to argue with The Man ?

[kmaier]

Hi All,

The V8 does have temp issues as many have pointed out. Basic problems are: 1- radiator capacity on the light side (for the V8) and 2- lack of airflow when in traffic. The cooling system is two parts, one water cooling and the other being oil cooling. The oil coolers are fine but realize that they only have airflow when the car is moving as there are no fans. With high ambient temps the oil coolers can heatsoak which results in a rise in temp. Second, the same applies to the radiator except the ECM will turn the fans on at 101C and back off at 90C. This is why you always see temp swings when you're in traffic, etc. When the A/C is engaged the ECM runs the cooling fans continuously but this still results in high temps as R-134a creates a lot of heat which is pulled thru the radiator via the fans so the effective cooling capacity of the radiator is lessened.

I replaced my radiator a while back. I worked with Griffin for a custom unit (ie, sent the original in as a pattern) which is a double 1-inch core all alloy unit with 3 11-inch Spal fans. It also weighs in with a 9 lbs savings. The new radiator is significantly better at reducing heat and as long as I'm moving temps are around 82C. With the A/C on (hence fans on) and high ambient temps over 90F the new radiator still keeps the temps down below 85C. Stop/Go traffic are no longer an issue but a slight temp rise still occurs for two reasons: 1- The oil coolers still have no airflow when stopped (or very slow speeds) and 2- Griffin fitted the very lowest CFM Spal fans to the unit and there are no shields and/or ducting beyond the fan shrouds themselves.

So, a few more bits todo for the perfect V8 cooling system as follows:

1- Use the medium speed Spal fans on the radiator (uses same mounting dimensions) to increase CFM.
2- Add Spal fans to the oil coolers to provide better regulation and eliminate heatsoaking.
3- Add additional sense/drive circuitry to power fans independant of ECM to ensure adequate airflow at ALL times.
4- Add an oil thermostat to regulate oil temp to a narrow (ie, optimum) range.

I'll be working on these over the next few months as the Esprit is getting close to "road vacation" and will live on the lift for a few months.

Regards, KM
2000 V8 (over 62K miles)

[deecee]

I would agree, but instead I would advise adding a Thermostatic Fan Control, rather than the Speed Sensing Control that it currently has.

The Spal fans are #30101500.

"the-fan-man.com" has them for $89 a piece.

They aren't the most high performance fan that Spal makes, but they are within the amp range for the Lotus.

[kmaier]

Hi Deecee,

Thanks... I also found the fan man and the pricing on the 0500 model. The higher performance 11-inch fan Spal make is a different motor/blade/shroud and has different mounting dimensions... and requires more current than the stock wiring reliably provides. I'm not aware of any speed sensing control however. Spal also make some smaller fans under ATV/Motorcycle use of which I found one which will fit the oil coolers.

Regards, KM
2000 V8

[deecee]

The ECU controls the fans and shuts them them down at...I believe...30 mph.

[kmaier]

deecee said:

The ECU controls the fans and shuts them them down at...I believe...30 mph.

I guess that's possible but I can't find any reference to that in the service notes for control of A/C and fans... only shows engine temps above 100C (off below 95C) and A/C compressor operation (via pressure switch) to turn the fans on/off. Circuit schematics confirm that A/C pressure switch has override on the fans (over the ECM) to keep the condensors cool. So if there is any speed sensitive control, it could only be the ECM turning the fans off if the engine coolant is over 100C and you're driving over 30MPH.

Regards, KM
2000 V8

[deecee]

Yeah, if the AC is turned on then the fans will run at all speeds, but with the AC off, the ECM controls the fans.

I found all this out when I retro'd the Delco Injection and ECM Wiring Harness into my S3.