Considering going turbo

mustangman408

mustangman408

Member
So as the title state, I'm thinking of going turbo on my upcoming 408 build. Problem is, I don't know squat about choosing a turbo. The searching I've been doing seems overwhelming. Too much info. I'm just trying to put some numbers together so I can figure cost and horsepower.

If a few of you guys could chime in I'd be grateful. Combo is as follows 408, edelbrock e-streets from fox lake, trick flow R intake, custom cam, C6, will decide on injectors when I figure out what my real needs are. Pump gas, air-to-air.

Thanks
 
I drove mine on the street as a daily driver but it has ran a high ten on a 357, all still smooth idling factory speed density. I had a Precision 76 millimeter with a T4 flange at 16psi through a power stroke diesel intercooler. A few guys running singles street drive T6 flange and 88 mm for really crazy power on stroker combos.
Check out Brian's thread, thinking he has a single 66mm setup and is quite impressive.
 
With a 408 your going to need a turbo that will flow a good amount of air. And I really mean on the exhaust side, otherwise you can run into backpressure issues on the turbine/ exhaust side. Compressor side doesn't mean as much as it used to. There are BorgWarner 300 series turbos that propel cars into the 8's. With that said you really need to determine what will be your most important needs of the turbo. Will it be max power or mean on the streets? A t4 based turbo that will light at will or a T6 based turbo that will have less ability to really make nice usable power on the street. I ran a tnetics 7668, it was awesome on the street and went 10.83 on the track with 14.5 psi. I can tell you right now I don't believe the turbo had much more and when I let off at the end of the track you could tell from the exhaust sound there was a ton of backpressure, probably above 3:1. I think a t4 s400, a precision Gen2 7675 would be awesome, especially if your not using a trans brake where you can get the turbo to make power for the launch. My turbo was small on the turbine, only 68 so I could make a pretty decent amount using a 2 step and the converter. If I were to put my brothers Ultra spec billet 76 1.32a/r T6 based turbo on. I would be lucky to launch with a couple psi and would probably overheat the trans in the process. Spooling those turbos even with a brake make makes the trans heat up quick. Temp will rise 70-80* in a few seconds.
 
Really need power goals in mind when choosing a turbo,
Either turbonetics or garret has a very nifty displacement vs hp chart to narrow down turbo choices.

That being said, I did none of this and chose mine because it was cheap ($800) it's a borgwarner s475 with a billet compressor wheel, 1.32 ar with the big 96mm turbine wheel.

It's a bit big for 351ci, it spools rather slow off the line, but I have several options down the road, bump up the stall, change out the turbine housing for a 1.1 ar, or just leave it for a while and go with a 408 striker eventually.
 
I tried the garret tool and they didn't show any options. The truck will see mostly street time but I want to lean towards the more track side of performance. Cause honestly who can tell the difference between 600 and 800 on the street in a full size pickup. I'm also not trying to make 1200 or anything. Knocking on the door of a grand would be fun but I may be limited by my heads and intake, its also a small bore motor.

Keep the opinions coming, thanks.
 
mustangman408 said:
....Cause honestly who can tell the difference between 600 and 800 on the street in a full size pickup....
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The power isn't where you would notice the difference. It's in how crisp it is driving around. To make 800hp you might be running 8:1 compression, but for 600 you might be able to up that 9:1 or even more. That makes a world of difference in how good it feels just driving around.
 
oilwell1415 said:
The power isn't where you would notice the difference. It's in how crisp it is driving around. To make 800hp you might be running 8:1 compression, but for 600 you might be able to up that 9:1 or even more. That makes a world of difference in how good it feels just driving around.
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Very good point. My 383 @ 9.37:1 with that 7668 was just plain nasty on the street and made driving always feel like the power was right there. Was it too small? Maybe. Still made 650 plus to the tire and was cheap(brothers) . If I was buying new I would have gone with something bigger on the turbine side.
 
oilwell1415 said:
The power isn't where you would notice the difference. It's in how crisp it is driving around. To make 800hp you might be running 8:1 compression, but for 600 you might be able to up that 9:1 or even more. That makes a world of difference in how good it feels just driving around.
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Good point. I think my compression is gonna be about 9:1 unless I can find a larger dish. I guess I could always tune it up for race gas when I take it to the track and push it a bit harder.
 
mustangman408 said:
Good point. I think my compression is gonna be about 9:1 unless I can find a larger dish. I guess I could always tune it up for race gas when I take it to the track and push it a bit harder.
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You could also run a thicker head gasket as well, but that's kind of a bandaid fix for poor planning during the build. Personally, if it was mine I would build it for the street with higher compression and then run race gas when I turned it up at the track.
 
oilwell1415 said:
You could also run a thicker head gasket as well, but that's kind of a bandaid fix for poor planning during the build. Personally, if it was mine I would build it for the street with higher compression and then run race gas when I turned it up at the track.
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Well I am definitely "redirecting here" I originally planned to simply spray the truck. So I've got to send the pistons back and either sell my custom cam or get it reground for turbo. But I definitely don't want more than .040 of quench. Although turbos may not make that as crucial?

So with pump gas on the street/race gas at the track in mind...Is there an area of A/R, wheel size, t4/t6, I should be looking for?
 
.96-1.15 a/r, 75mm exhaust wheel at least. I personally would do a t4 simply because unless it's going to be an all out race venture, I don't think you'll be happy with it's street manners. It will be lazy. My brothers ultra car is a t6 based turbo that makes 1150 at the tire. Go's like heck at the track, but on the street just driving it's like there is no turo there for a while. It's also an 11.3:1 motor and runs low 8's. Want to take a look at a bad street car/ tru street set up, look up Mike Jovanis and his t4 based monster that runs 7's. Just my .02 cents what do I know.
 
mustangman408 said:
Well I am definitely "redirecting here" I originally planned to simply spray the truck. So I've got to send the pistons back and either sell my custom cam or get it reground for turbo. But I definitely don't want more than .040 of quench. Although turbos may not make that as crucial?
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What is your compression now? If it's under 10:1 I'd just leave it and run low boost when you're on pump gas. Maybe even leave the cam alone. For a street truck I would build an engine that would be fun NA, then use boost to supplement it. For a race truck, I would built the engine around the turbo from the start.
 
oilwell1415 said:
What is your compression now? If it's under 10:1 I'd just leave it and run low boost when you're on pump gas. Maybe even leave the cam alone. For a street truck I would build an engine that would be fun NA, then use boost to supplement it. For a race truck, I would built the engine around the turbo from the start.
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Well I'm currently running the stock shortblock with powerdyne, ported performers, and a lunati cam. All that's coming out for a 408 I've been gathering parts for. The stock short block is worn out, heads are junk. Ive got new heads, intake, cam, pistons, and crank for the 408. But the current pistons would put me over 10:1. So I'm gonna see if I can return them to DSS for a deeper dish.
 
Two important questions need to be answered. Are you sticking with the stock block and what fuel do you plan on using. 10 to 1 compression is fine if your running E85. Stock block will only handle 600-700 rwhp reliably. Smallest turbo I would use would be a 76 with bigger exhaust housing. An 80-88mm would be a little more suited on a 408. Hey, but what do I know.....:D
 
Modern Muscle said:
Two important questions need to be answered. Are you sticking with the stock block and what fuel do you plan on using. 10 to 1 compression is fine if your running E85. Stock block will only handle 600-700 rwhp reliably. Smallest turbo I would use would be a 76 with bigger exhaust housing. An 80-88mm would be a little more suited on a 408. Hey, but what do I know.....:D
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I'll be using a stock block for now, but I've pushed the stock block pretty far in our drag car....so I guess I like living on the edge :cool: I really would like to be in the 700-800 range. Compression will be 9:1 so I assume I may need race/pump mix to make that, will a smaller tune for the street.
 
I'll share what I did with mine. Designed the tune around 93 octane, which I can get from the pump. Max timing 15* above 9 psi. Kept the a/f not rich, but a little more safe than I would with a good block and race gas. At the track I would basically just mix in enough VP110 so I had a 75/25 mix of gas and would leave the tune alone. Never had the truck on a dyno but we figure from the results I was making 650 or so. Was I giving up power? Yes, but I had a combo that drove anywhere and moved pretty good. I felt comfortable with the engine at that power level, anymore not so much. Which is why I built the Dart motor.
Is your new motor neutral balanced, that makes a stock block even more happy.
 
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