Re: Building on the forced induction post.
[Re: TRENDZ]
#2848511
11/19/20 09:35 AM
11/19/20 09:35 AM
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Joined: May 2019
Posts: 722 Lake Villa Il
INTMD8
super stock
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super stock
Joined: May 2019
Posts: 722
Lake Villa Il
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Yes but this is all a balancing act. On the other end of the spectrum there are many turbos out there with too large of a compressor vs turbine (like 76/66) and that will result in the same problem, excessively high drive pressure.
That's why I think twins are better every time. For a given potential airflow you end up with faster response and less drive pressure compared to a single.
69 Charger. 438ci Gen2 hemi. Flex fuel. Holley HP efi. 650rwhp @7250 510rwtq @5700
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Re: Building on the forced induction post.
[Re: INTMD8]
#2848515
11/19/20 09:40 AM
11/19/20 09:40 AM
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Joined: Jan 2005
Posts: 2,540 Milwaukee WI
TRENDZ
master
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master
Joined: Jan 2005
Posts: 2,540
Milwaukee WI
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Agree about the balancing act, but the turbo you mention is hard to beat on a 5000 rpm v6. All caters to many variables. Testing testing testing.
Last edited by TRENDZ; 11/19/20 09:41 AM.
"use it 'till it breaks, replace as needed"
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Re: Building on the forced induction post.
[Re: TRENDZ]
#2848520
11/19/20 09:54 AM
11/19/20 09:54 AM
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Joined: May 2019
Posts: 722 Lake Villa Il
INTMD8
super stock
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super stock
Joined: May 2019
Posts: 722
Lake Villa Il
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IMO it's just a mismatched unit. I would rather the compressor and turbine be capable of similar power levels. So if I have 750hp worth of turbine give me a 66mm compressor instead of less response from a 76mm capable of 1000.
69 Charger. 438ci Gen2 hemi. Flex fuel. Holley HP efi. 650rwhp @7250 510rwtq @5700
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Re: Building on the forced induction post.
[Re: TRENDZ]
#2848524
11/19/20 10:06 AM
11/19/20 10:06 AM
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Joined: Sep 2008
Posts: 656 Florida
CJD AUTOMOTIVE
mopar
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mopar
Joined: Sep 2008
Posts: 656
Florida
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I would stick with a turbo that has compressor maps available, BW or Garrett. Your unlikely to find someone running a combo that will be similar, so trying to find a proven combination is not going to be GM LS easy. Both BW and Garrett have programs, Match Bot , and they are very good. Make sure your data entered is accurate, and pay attention to where you are using the turbo in it's compressor map. I like the MatchBot because I can make changes to the formula to best make use of a combination. I am running twin EFR 9180 turbo's with Tial 1.02 housings. Using MatchBot, this was the best compromise for staying in the efficient part of the compressor, spool time, and EMAP (back pressure in the manifold).
Craig Scholl CJD Automotive, LLC Jacksonville, FL www.CJDAUTOMOTIVE.com904-400-1802 "I own a Mopar. I already know it won't be in stock, won't ship tomorrow, and won't fit without modification"
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Re: Building on the forced induction post.
[Re: CJD AUTOMOTIVE]
#2848620
11/19/20 01:11 PM
11/19/20 01:11 PM
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Joined: Nov 2006
Posts: 2,265 IL
furious70
top fuel
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top fuel
Joined: Nov 2006
Posts: 2,265
IL
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Makes sense @feets @TRENDZ
For those of us who are hobbyists vs hard core, you shouldn't discount the amount of fabbing and cutting. Twin T4's might be the best theoretically but be terribly difficult to package in a car that needs to maintain it's OEM inner fender wells and such for other reasons. A single might be easier to package for most cars with power brakes and power steering. A T6 is a BIG thing to fit as is a 5" downpipe. A single T4 turbo can be the easiest item to package and be successful for a hobbyist. Matching your cubic inches to a turbo size that you can package, e.g. feets' original beast may have been better served with a 383/400 making the same or better power more comfortably/economically.
I have a 383 in my Fury for a reason vs a 440 or stroker. I'm using a 5.7 in my Coronet for a reason - allowing me to more easily package appropriately sized turbos and still have the capability to make more power than I'll use/install safety equipment for.
70 Sport Fury 68 Charger 69 Coronet 72 RR
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Re: Building on the forced induction post.
[Re: furious70]
#2848734
11/19/20 04:24 PM
11/19/20 04:24 PM
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Joined: Jan 2003
Posts: 28,096 Irving, TX
feets
Senior Management
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Senior Management
Joined: Jan 2003
Posts: 28,096
Irving, TX
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For those reading who aren't intimately family with turbos... Turbos are not free power.
In this world you don't get something for nothing. The same goes with boost. Any real street car with a turbo will have more pressure in the exhaust than in the turbo. Compressing air takes work.
Oh, but it's exhaust gas you say. Your breath is exhaust gas. Ever notice you have to put a little effort into blowing up a balloon? Try blowing up a car tire to 20 psi. Think you'll get there by puffing on a valve stem?
The engine is experiencing the same issue. It has to work to build up that pressure. However, instead if a fixed container, it has to maintain that level of work until you get off the throttle.
Turbo lag? That means the engine hasn't worked hard enough to get the turbo up to speed.
Turbos can be very efficient but they aren't free.
We are brothers and sisters doing time on the planet for better or worse. I'll take the better, if you don't mind. - Stu Harmon
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Re: Building on the forced induction post.
[Re: INTMD8]
#2848979
11/20/20 10:54 AM
11/20/20 10:54 AM
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Joined: Jan 2005
Posts: 3,639 Oakland, MI
dizuster
master
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master
Joined: Jan 2005
Posts: 3,639
Oakland, MI
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I guarantee you that if you log your exhaust pressure now, with the current engine
I'll guess 53psi turbine drive with 23psi at the intake I have not measured it, but I do have some information. I only run a 2psi wastegate spring, and rely on the boost controller (on board air tank) pressure into the top side of the gate to make the boost. Basically it requires 1psi of gate pressure, to make 1psi of boost. If the backpressure was at 53psi, it would be blowing that 2psi gate spring open for sure. Also, the car does not like RPM regardless of boost pressure. Even at 10 or 15psi it doesn't like RPM (ET slows down if you shift it higher). But in principal, I do agree any combo can benefit from lower backpressure. 100% agree with that. But it's not the end all, be all, of a combo. I would think a S480 combo (80/88) at 850hp goal is a great choice for the original poster. 80mm compressor will make 850 easily, It will spool relatively quick, and the China Knock off versions can be had for $750 or so in billet wheel form. I can't see doubling the complexity and cost with Twins being worth it in a build like that.
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Re: Building on the forced induction post.
[Re: dizuster]
#2848993
11/20/20 11:30 AM
11/20/20 11:30 AM
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Joined: May 2019
Posts: 722 Lake Villa Il
INTMD8
super stock
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super stock
Joined: May 2019
Posts: 722
Lake Villa Il
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Easy way to find out is to measure it. Probably 10 minutes worth of work if you are interested in finding out.
Twins aren't double the cost or complexity. Just depends on your goals.
Yes you can make almost any power goal with a single turbo. If at the same power level you want much faster response and the ability to hit peak boost/torque at a lower rpm on a street car, twins will make that happen.
Last edited by INTMD8; 11/20/20 11:31 AM.
69 Charger. 438ci Gen2 hemi. Flex fuel. Holley HP efi. 650rwhp @7250 510rwtq @5700
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Re: Building on the forced induction post.
[Re: INTMD8]
#2849009
11/20/20 11:54 AM
11/20/20 11:54 AM
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Joined: Mar 2006
Posts: 9,982 MI, usa
dvw
master
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master
Joined: Mar 2006
Posts: 9,982
MI, usa
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[u][/u]I've driven Dizusters car on the street. It's hard to manage the "response" now. It doesnt need anymore. A 5 second burst gets you to where you dont need to be on the street. Racecar is a different story. We can always go faster. Doug
Last edited by dvw; 11/20/20 12:26 PM.
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Re: Building on the forced induction post.
[Re: dvw]
#2849015
11/20/20 12:02 PM
11/20/20 12:02 PM
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Joined: May 2019
Posts: 722 Lake Villa Il
INTMD8
super stock
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super stock
Joined: May 2019
Posts: 722
Lake Villa Il
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Yes all preference. I feel single turbos are harder to manage as you can go wide open throttle and get a big thump of boost as it hits.
Twins can almost follow the accelerator pedal as far as response so easy to roll into it and maintain traction.
That and more so, just response during part throttle driving.
69 Charger. 438ci Gen2 hemi. Flex fuel. Holley HP efi. 650rwhp @7250 510rwtq @5700
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Re: Building on the forced induction post.
[Re: INTMD8]
#2849044
11/20/20 12:55 PM
11/20/20 12:55 PM
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Joined: Jan 2005
Posts: 2,540 Milwaukee WI
TRENDZ
master
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master
Joined: Jan 2005
Posts: 2,540
Milwaukee WI
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Yes all preference. I feel single turbos are harder to manage as you can go wide open throttle and get a big thump of boost as it hits.
Twins can almost follow the accelerator pedal as far as response so easy to roll into it and maintain traction.
That and more so, just response during part throttle driving. Agree. Changed over a customer car to twins from a single. Much more predictable and followed the throttle better. A bigger single gives that “2 stroke” feel of a power rush.
"use it 'till it breaks, replace as needed"
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Re: Building on the forced induction post.
[Re: TRENDZ]
#2849049
11/20/20 01:02 PM
11/20/20 01:02 PM
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Joined: May 2019
Posts: 722 Lake Villa Il
INTMD8
super stock
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super stock
Joined: May 2019
Posts: 722
Lake Villa Il
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A bigger single gives that “2 stroke” feel of a power rush.
For sure, great analogy.
69 Charger. 438ci Gen2 hemi. Flex fuel. Holley HP efi. 650rwhp @7250 510rwtq @5700
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