Engine/Transmission (1994 - 1998) which turbo would be best HTT 62/12 or 62/14

[KHelfrich]

looking at getting a new turbo either a 62/12 or a 62/14 i run mostly empty will have custom EDM 370's high flow delivery valves #10 full forwary 3kgsk AFE intake and 4 inch straight pipe and the truck is a 6 speed and i have 3. 55 gears all opinions welcome



ken

 

[pwerwagn]

I would pick the 14 over the 12 for the following resons:



less chance of surge

less drive pressure

more room for growth, power wise. Plus, if you ever wanted to upgrade to a 64/14 or 66/14 it would be somewhat easier I presume.



BTW, I got the check in the mail for the shocks. Thanks for all your help man. .



--Jeff

 

[KHelfrich]

forgot to mention i also want to use this turbo as the top turbo in a set of twins in the future if that changes anything



ken

 

[zstroken]

62/14 would probably be the best if you were just going to stay with a single, but since you mentioned twins 62/12 might be a good way to go. I have had no one complain to me about surging with the 62/12. I have one on my truck and several customers have purchased them and no complaints of surging.

 

[foolkiller]

i love my 62/12 turbo..... a little tired of listening to it but it performs really well with a rare bark under very specific conditions. low exit temps, quick spool, smooth power. the noise is pretty easily overcome with some music.



good luck, jeff

 

[Cooker]

I would opt for the 14. If you were towing a lot the 12 might be a little better. JMHO

 

[KHelfrich]

maybe i wrong but i thought when towing you want the bigger exhauts housing cause you work the motor harder and keep high boost levels for extended time but when running empty you want the smaller housing so it spools fast and you really arent demanding high power and boost for extended periods of time



Please let me know if what im thinging is wrong



ken

 

[Matthug]

When towing you want the smaller housing because there will be more boost present which means lower EGT's. Faster spoolup is also nicer when towing, less smoke too.

Personally I would go 14 because I like keeping drive pressure's down... . but it's really a tough decision because you plan to go with twins later and with twins the 12 would probably be better.

 

[Cooker]

When towing you want the smaller housing because there will be more boost present which means lower EGT's. Faster spoolup is also nicer when towing, less smoke too.

Exactly.



Ken if your truck had 4. 10's I would say go with the 14 housing. Since the truck has 3. 55's I would go with the 12 housing without a doubt.



If you do not tow much then I would consider the 14 housing.



This advice comes from my expeience with two similar turbos. I had a HTB2 62/12 and now have a 62/14 from II. When towing with 3. 55's and the 62/14 it is hard to tow around 65MPH in OD and keep everything cool. With OD locked out and RPMs at 2300-2400 it is fine but MPG's suffer. It tows much better at 75MPH than 65MPH but depending on what I am towing I may not like to travel at 75MPH.



This is all in the relatively flat state of Michigan. In a more mountainous state the problem would be even worse.

 

[KHelfrich]

Cooker or anyone



what is the advantage of the 62/14 it has lower drive pressure and spools slower i thought the lower drive pressure is good cause it lowers egt but is the 12 has lower egt why would you want the 14



by the way the way i drive i usally curise around 1800-1900 rpm and when i pulling out i usally dont rev much past 2600 rpm if that makes a drffierence with the housing i chose



one last thing when running twins dont you want both housings to be big so all the exhaust from 60 lbs of boost can flow easily or do you need a small primary to achive the high boost pressures



thanks fo all the help

Ken

 

[Cooker]

what is the advantage of the 62/14 it has lower drive pressure and spools slower i thought the lower drive pressure is good cause it lowers egt but is the 12 has lower egt why would you want the 14

The 14 does have lower drive pressure and lower peak EGT's. It should also have slightly more peak HP. Better peak numbers don't necessarily equate to better towing numbers or to a more streetable truck.



As I said I think the biggest issue to consider is gearing. if I had 4. 10 gears and the RPM's were greater the 14 would less of a concern while towing. Don't get me wrong the 14 is not that bad but you do have to think a lot more when towing with the 14 than with the 12.



[quote[

one last thing when running twins dont you want both housings to be big so all the exhaust from 60 lbs of boost can flow easily or do you need a small primary to achive the high boost pressures

[/QUOTE]



The short answer to your question is no. As with choosing a single turbo exhaust housing selection is very important in determining how your setup will actually perform and taking your use for the truck into consideration is just as important. BTW - If you are referring to 60lbs of boost neither the secondary or the primary is making 60lbs of boost on it's own.

 

[zstroken]

one last thing when running twins dont you want both housings to be big so all the exhaust from 60 lbs of boost can flow easily or do you need a small primary to achive the high boost pressures

Get the 12 cm and put an external on it. They you can have the fastest spool as possible.

 

[KHelfrich]

zstroken



so your saying get the 62/12 now and it will have the internal wastgates and then when i go to twins add an external wastgate in the manifold then i will have internal and exturnal wastgates



ken

 

[zstroken]

zstroken



so your saying get the 62/12 now and it will have the internal wastgates and then when i go to twins add an external wastgate in the manifold then i will have internal and exturnal wastgates



ken

It depends on how much HP you are looking to have down the road. If you want BIG HP the internal wastegate will not bypass enough to keep the drive pressures in check. Do a search on wastegates and twins, there was some good discussions about it a while back.