MPG with Turbo upgrade

[WoodChuck]

I recently upgraded my turbo to the HTB2 62/14 and did a mileage check. It seems to have gone down about 2 MPG.

I don't know if it was ULSD or LSD fuel but I expected at least the same mileage or maybe even better.

What kind of results has everyone else got with their turbo upgrade?

 

[WoodChuck]

Anybody check their mileage after a turbo upgrade???

 

[WCPoe]

Yep - I lost an average of 1 to 1 1/2 mpg when I installed my SPS66. I had been spoiled because when I did the ATS trans upgrade earlier I had picked up about the same mileage increase because the converter was a lot tighter and the trans controller allowed me to keep it locked at lower speeds.

When I added the turbo, which was several months after the transmission upgrade I realized my mileage was down. Granted I didn't keep a detailed mileage log but did hand calc my mileage regularly.

I think the bigger turbo is just a little harder to spool and therefore a little less efficient. Although, it may have been partially resultant of trying to throw more fuel at it to get it to spool. Just my 2 cents.

 

[WoodChuck]

I'm thinking the bigger turbo should be more efficient under load but for unloaded flat cruising it's a little less efficient than stock.

 

[JStieger]

I'm thinking the bigger turbo should be more efficient under load but for unloaded flat cruising it's a little less efficient than stock.

When I switched from stock to HTB2 62/12 then to HTB2 62/14 I didn't notice any noticeable mileage loss. In fact, I gained mileage going to the HTB2 62/14 because I changed to a PDR cam at the same time.



When I switched to a SPS 66 from HTB2 62/14 I lost 2 mpg. Low boost at cruise = constant haze or smoke trail. Under load, even with higher boost, I had a constant smoke trail unless I drop to 5th and wind it up... or stay in 6th and run 85 mph plus towing - neither condition is conducive to optimum mileage.



From the SPS66 I switched to a SPS62 and gained about 1. 5 of the lost 2 mpg back. With any of the SPS turbos my empty cruise EGT was about 900-1000*. A few years ago in one of the TDR magazines was an article that stated the best mileage was under 10 psi boost AND xxx* EGT. I like to think that that EGT number was 700* or so.



From the SPS62 I went to BD twins and my mileage has increased back to HTB2 62/14 levels. The BD twins have the small 57mm Super B on top, but have cost me about 17 HP to run the extra turbo.

 

[HighRanger]

Damn, I will keep an eye out. I am in the middle of installing my ats manifold and sps 62/14 now. I'll post back up in a day or so. Right now I am averaging about 18-20 depending on how I drive.

 

[jjdiesel]

I gained between 1. 5 and 2 mpg when I changed the stock set-up to a SPS62 with the ATS manifold. I've always hand calculated my mileage, quite meticulously I might add. With the change, I've noticed more of a distinction between Hwy mileage and City. With the stock truck, there was never that much difference between the two, now when I jump on the Hwy for a reasonable length of time my mileage really shoots up there... . I think the drive pressure with this turbo is much more efficient overall than stock. I alson have DD injectors (90hp) and a 4" exhaust system. hth