Need assistance w/ KB 2.8h

[brianstrawberry]

Guys, i finally pulled the trigger on a KB 2.8h and need some help from the pros in getting the most out of it. :banana:

So far under the hood I have the following that would go into my build:
o/r Prochamber, Borla Stingers
JLT intake
Accufab SB TB w/ plenum
diablo tuner

I have 60# injectors, MAFia, BAP with wire upgrade, a 4# lower w/ alt pulley, Evenflow cooling mod and
a few gauges ready to go to support the blower upgrade (though the lower might not be necessary).

My goals here on the dyno are 600-630 rwhp and 600-range tq...

The car will probably not see the track and only be used on nice weekend days. That said, I don't mind buying 93 octane fuel but don't want to go with a race-gas setup. I am aware that the 2.8h is best suited for a built motor (which I love about it due to room for growth), but this would not be for another year or two.

The supercharger currently has no pulley on it and I would love some input as to what size pulleys would be recommended for my goals along with anything else needed to get me there.

op::bowdown:

 

[Fatal Strike]

Well, I have a stock lower and a 3.5 upper pulley on mine and I'm only seeing 16-17 pounds... I do have ported heads and stage 3 crower cams though so thats absorbing some of mine, I have a built motor though and I'm trying to get 24#'s so I'm bout to have to completely change my pulley arrangments.. what boost are you wanting to run? I would recommend staying around 17 pounds for pump gas... but your 2.8 is not really gonna shine unless your over that so I would suggest a higher boost race tune to have just in case

 

[GodStang]

Here is what the typical boost will run on a stock engine. With your setup you should run a 4-1/4" with the 4# lower to get the 17-18psi to run 93 Octane. I am not sure if that upper will fit under the stock hood. You may be better off going to a 2# lower and a 4" upper or even the stock lower and 3-3/4" upper.

 

[Teal Terminator]

I have run the 4# lower and 4" upper and in warmer weather would see 19-20 psi. Since it got cold I've had a 2# lower on it (still with the 4" upper) and I seem to see around 17-18 most of the time and peaks of 19 psi above 6000 rpm sometimes. Keep in mind I also have LT's and some mild head porting which might be bringing my boost down just a touch compared to what yours will be. So I would suggest getting a 2" lower and running it with either a 4" upper or 3.75" upper. I'm not sure they make a 4.25" upper and like Godstang said, even if they do I'm not sure it will clear the stock hood.

Good luck,
Ryan

 

[brianstrawberry]

I like the idea of the 3 ¾” upper only, but from what I understand, I would be losing torque without a lower. What boost and dyno numbers could I expect (or you guess) to see with the 3 ¾” (or 4”) upper paired with a 2# lower? It sounds like from the comments so far that 19-20# boost is about max that 93 octane will handle with a safe tune in the 17-18# range. Will these get me to my goals?

Also, is anyone able to help me understand pulley ratio in the above table?

Teal, where did you get your car tuned in or around Raleigh, Fastlane? Haywood?

 

[blackvenom77]

You won't lose torque without a lower, that's just an old wise tale. Just limit your belt slip and you will be fine.
Boost is boost your motor can't tell if you have a lower or not.

 

[MaximumVelocity]

Didn't see fuel pumps on your list of supporting mods.:??:

 

[GodStang]

You won't lose torque without a lower, that's just an old wise tale. Just limit your belt slip and you will be fine.
Boost is boost your motor can't tell if you have a lower or not.

^^Ya what he said. The loss of belt slip helps.

Didn't see fuel pumps on your list of supporting mods.:??:

He said BAP but I would think he would be better off with Fore hat and Dual GT Pumps.

 

[brianstrawberry]

The parts listed ready to go on are from last summers efforts to get a stg. 4 ported Eaton on the car. I never put them on due to the attractiveness of a twin screw.

From what I have read, the BAP will take me into my goal territory but would need to be swapped out if I wanted to go any further.

BTW great input on the lower... I learn something new everyday

 

[brianstrawberry]

I found this on KB's website to help me with pulley sizes:

"PULLEYS, RATIOS & BOOST - See chart for boost numbers. Plus (+) psi boost numbers (+2 psi, +5 psi etc) is a non scientific, inaccurate and confusing method of rating pulleys. At Kenne Bell, we prefer to also use "ratios" (crank pulley ÷ supercharger pulley = ratio) to describe a potential boost increase. In other words, list the boost AND ratio. Why? Is a supercharger pulley a +2 with the stock 7.5", 9" or ? crank pulley? And is the +2, +4, +6 crank pulley with a 3.5", 3" or 2.7" supercharger pulley? To make matters more confusing some superchargers, such as the Eaton, do not develop the same boost at 2000, 3000, 4000, 5000 and 6000 rpm. They suffer from "boost drop off." For example: What plus (+) pulley rating do you give a Cobra '03 pulley that is 15.3 psi at 4000 but only 10.3 at 6000 when the stock pulley was 8.3 at 4000 and 7.8 at 6000? We refer to the stock pulleys as a 2.11 ratio and 7.8 psi (7.5" ÷ 3.55" = 2.11 ratio) and the 3" pulley as a 2.5 ratio and 10.4 psi (7.5" ÷ 3" = 2.5 ratio). Now take the same 3" pulley with a 9.25" crank pulley and you have a 3.1 ratio instead of a 2.5 ratio. On our superchargers, that's around 6 psi variance. Get the point? Kenne Bell lists the ratios and boost for all applications. We offer Lightning/Harley SC and crank pulley combinations of 9.5, 11, 14 and 16 psi. The Cobra combinations are 10.4 and 13.3 with sc pulleys only. Note: We don't recommend a larger crank pulley for the Cobra Eaton, but for those who prefer one, we have an 8.25" Cobra which works with the Eaton or Kenne Bell. Want to know if your supercharger is producing the boost it's supposed to."

There is also an equation that they use given SC size, Engine size, and pulley ratio that gives expected boost which I have been playing with.

equation is: Boost = (((SC size*Pulley Ratio)/(Engine liters/2))*14.7)-14.7

Link: Pulleys / Pulley Puller Tool

What I have found from this is that with a stock lower of 7.5 a 3.75 upper would make 21# and be out of the safety zone. While a 4 upper would be right at 18.5.

Yes, this is contradictory to the table above unless you size the KB 2.8h at 2.6. Additionally, the equation works the same with the 2.6.

Soooo is the 2.6 actually a 2.4 and the 2.8 a 2.6 or am I missing something here? Maybe this is just news to me, or maybe the table above is incorrect?

 

[unit213]

that's just an old wise tale. Just limit your belt slip and you will be fine.

...or perhaps an old wives tale?

Agreed though.

 

[GodStang]

...or perhaps an old wives tale?

Agreed though.

hahaha

 

[droptopsnake01]

I like the idea of the 3 ¾” upper only, but from what I understand, I would be losing torque without a lower. What boost and dyno numbers could I expect (or you guess) to see with the 3 ¾” (or 4”) upper paired with a 2# lower? It sounds like from the comments so far that 19-20# boost is about max that 93 octane will handle with a safe tune in the 17-18# range. Will these get me to my goals?

Also, is anyone able to help me understand pulley ratio in the above table?

Teal, where did you get your car tuned in or around Raleigh, Fastlane? Haywood?

I don't think Teal had his car tuned at either shop.

Fastlane did my build/tune. Great guys.

 

[Teal Terminator]

I had Ed Clark tune my car. He used to tune through a shop in the Virginia Beach area but I'm not sure that shop is there any more. He still will tune if you go to him or even down here if he is in the area. Obviously you just have to rent some dyno time somewhere.