Dennis5374

I'm just curious but instead of running a 408 with twin 7868 turbonetics "Benita" would I be better off running a 6.0 with stock displacement to negate back pressure issues ? I'm completely new too the turbo scene , but from what I gathered , the bigger the engine , the more turbine required. Also would I be able to reach my hp goals "1000 rwhp " and "1400 rwhp on kill" ?both would be through Holley dominator efi , water/meth injection , only difference being 93 octane for the 1000 rwhp goal and ms-109 for 1400 rwhp. I already own the turbos , as well as 15k in parts that are all getting installed throughout the winter. I just want what will work best with the turbos I already have .. I'm estimating the total cost of the car from front to back to be north of 25k easily.

stevieturbo

And what backpressure issues do you think you will have ?

Presumably you have no motor at all ? The smaller motor may well run the compressor more efficiently, albeit at higher boost. But I wouldnt get too worked up about it either way

Although does the 78mm refer to the inducer or exducer ? Power quotes do seem low for a 78mm inducer turbo ?

Worst case if the larger motor didnt work....it's just a case of getting larger turbos. Simple and relatively inexpensive upgrade.

Dennis5374

compressor Wheel is a 78mm , turbine is a 68mm. Quite a few members have stated this turbo is "way" to small for a stock ls1 and either a: I'll run out of steam up top or b:the relatively small exhaust side will cause back pressure issues .I have a perfect running 6.0 with 60k miles sitting on my engine stand at The shop . My original plan was to build a 427 lsx, but seeing multiple 6.0 based turbo builds living north of what I'm trying to do , seems logical to save 3000.00

stevieturbo

2 of them most certainly will not be too small. 1 would though

If these people claiming it will have backpressure issues...lets see the evidence.

Dennis5374

Well next Friday I will be running a single on a bone stock cam only ls1. Once snow hits , the overhaul begins . So a pair on a 408 should be fine then? I'd rather go with the extra displacement . I'll be running a Holley dominator stand alone, nasty n8 fuel system, crp fab9 and a tick performance level 5 tr6060. I just want a 9 flat capable m6 car that is gonna be a lot to handle at tx2k in the roll race event . I'm putting a lot of time and money in this build , and intend on keeping it for quite some time

stevieturbo

I would just go with the larger engine. As said, worst case scenario, just change the turbos later, as that's a fairly simple task.

As for 9 flat...if it's light enough and grips well enough it is doable.

I certainly dont see the turbine being restrictive, I've 6468 BW's on my 383 and at pretty much all times EGBP vs Manifold pressure is 1:1
Your motor will be larger...but I still dont see that making a huge difference.

How my "64" would compare to your "78"...as said, depends what that 78mm refers to. If the inducer, it sounds like a very poor airflow for the size as even my 64mm wheel flows the same, if not a little more.

Dennis5374

These are the specs I have , I've always had nitrous cars and one single supercharged car. So this is very new too me . But I'm the kind of person that if I'm gonna do it, I'm gonna do it big and go overkill on everything . The engine, fuel system, rear etc will all be up too the task of supporting double my goal, and according to this those turbos in a pair should get me up around 1400 spinning the hell out of em

stevieturbo

Obviously the above is a generic image....TN's own site it does appear to be a billet wheeled unit ( if TN's image is correct ), which makes the flow claims again either very conservative, or quite low for a 78mm inducer turbo, if that is the measurement they use

https://turboneticsinc.com/store/ind...&product_id=84

Dennis5374

I got a smoking deal in two of them for around the price of 1 . 1 was brand new in the box, the other was used for one season the swapped for a larger turbo. I guess the dyno will tell where it makes power too, and give me a better idea how well it'll suit the car . I'll have it all installed and ready to go by next Monday. I'm gonna use the afr target tuning software with the dominator efi to get a safe tune in ,and to get me to the dyno . If I can make 600 at the tires with a single and mostly stock 5.7 , I see no reason that with a 408 and twins j can't double that