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Turbo theory: fuel and timing requirements
http://www.teamswift.net/viewtopic.php?f=6&t=13605
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Author:  Bigbearzuke [ Mon Mar 28, 2005 3:53 pm ]
Post subject:  Turbo theory: fuel and timing requirements

I’ve been meaning to write this info for a long time. This will help people in setting up their turbo motor properly. This info is based on calculations and theories taken from the net, tuning programs and calculations based on commercially available info for dyno calculators. These recommendations are based on ideal situations and should be used as a reference only. These equations do not take into account altitude, humidity, temperature, etc… unless where noted. They also assume you have adequate fuel, air-flow, and cooling capacity for your motor. All info is to be used at your own risk.


Fuel and timing requirements for boost:

1. Boost: Amount of boost in PSI.
2. Effective compression ratio: Total compression ratio of motor with boost and base compression calculated in.
3. Required octane: Octane rating recommended for effective compression ratio (R+M)/2 method.
4. Octane run: Actual octane fuel used (R+M)/2 method.
5. Boost retard: Amount of retard required for Octane run. Based on the fact that no addition detonation control used (RRFPR, FMU, Water/Alcohol injection etc…)
6. Retard per PSI: Amount of retard needed for each PSI of boost.

Calculations based for a stock 10:1 compression motor with stock timing.

1. 2. 3. 4. 5. 6.
4 PSI 12.7:1 89.7 91 +2 +0.6
5 PSI 13.4:1 91.3 91 1 0.1
6 PSI 14.1:1 92.9 91 3 0.5
7 PSI 14.8:1 94.4 91 6 0.8
8 PSI 15.4:1 95.8 91 8 1.0
9 PSI 16.1:1 97.2 94 5 0.6
10 PSI 16.8:1 98.5 94 7 0.7
11 PSI 17.5:1 99.7 94 10 0.9
12 PSI 18.2:1 100.9 94 12 1.0
13 PSI 18.8:1 102.1 94 14 1.0
14 PSI 19.5:1 103.2 94 15 1.1
15 PSI 20.2:1 104.3 94 17 1.1


Calculations based on an 8.5:1 compression motor with stock timing.

1. 2. 3. 4. 5. 6.
4 PSI 10.8:1 84.5 91 +11 +2.7
5 PSI 11.4:1 86.2 91 +8 +1.6
6 PSI 12.0:1 87.7 91 +5 +0.9
7 PSI 12.5:1 89.2 91 +3 +0.4
8 PSI 13.1:1 90.6 91 +1 +0.1
9 PSI 13.7:1 92.0 94 +3 +0.4
10 PSI 14.3:1 93.3 94 +1 +0.1
11 PSI 14.9:1 94.6 94 1 0.1
12 PSI 15.4:1 95.8 94 3 0.2
13 PSI 16.0:1 97 94 5 0.4
14 PSI 16.6:1 98.1 94 7 0.5
15 PSI 17.2:1 99.2 94 9 0.6

You may notice positive or advanced numbers in the above equations it’s not recommended that you advance your timing. It would be better to pull fuel from the equation for better BSFC. You can compensate the amount of retard required by adding more fuel to control detonation but this will raise your BSFC.


Potential power gain from turbo charging:

This is a rough estimate of the potential power gains from turbo charging:
This is based on theory with figures taken from above as reference. Real conditions can differ
Based on a 100 HP motor.

4 PSI 127 HP
5 PSI 134 HP
6 PSI 141 HP
7 PSI 148 HP
8 PSI 154 HP
9 PSI 161 HP
10 PSI 168 HP
11 PSI 175 HP
12 PSI 182 HP
13 PSI 188 HP
14 PSI 195 HP
15 PSI 202 HP


Compressor temperatures:

For those of you who think they don’t need to run an intercooler here are some calculations of compressor exit temperatures. This is based on an inlet temperature of 80 degrees F. and a compressor efficiency of 70%. This dosn’t take into account heat generated by the exhaust. This is friction heating alone.

4 PSI 133* F.
5 PSI 145* F.
6 PSI 157* F.
7 PSI 168* F.
8 PSI 179* F.
9 PSI 189* F.
10 PSI 199* F.
11 PSI 209* F.
12 PSI 219* F.
13 PSI 228* F.
14 PSI 237* F.
15 PSI 246* F.

These exit temperatures will effect your overall turbo fuel and timing requirements.


Engine size calculations:

Allot of people have difficulties calculating their engine size after over-boring their cylinders. Here are some displacement sizes for different bore sizes

The stock 1.3l motor has the following bore X stroke = displacement in CC and CID

74 mm X 75.5 mm = 1298 cc or 79 CID (stock motor)
74.5 mm X 75.5 mm = 1316 cc or 80 CID
75 mm X 75.5 mm = 1334 cc or 81 CID
75.5 mm X 75.5 mm = 1352 cc or 83 CID (considered 1.4l)
76 mm X 75.5 mm = 1370 cc or 84 CID
76.5 mm X 75.5 mm = 1388 cc or 85 CID
77 mm X 75.5 mm = 1406 cc or 86 CID
77.5 mm X 75.5 mm = 1425 cc or 87 CID
78 mm X 75.5 mm = 1443 cc or 88 CID

Boring a motor 77 mm or larger requires sleeving of the block to accommodate the larger pistons. Boring a block 76 mm or larger should be sonic tested to ensure there is enough metal to bore it larger.

Again this information is for reference only and your motor/conditions can differ than what was provided above. I will add to this when I get more time. All info above is to be used at your own risk

Sorry I can't get it to format properly. I will try to fix the problem so you can read it better

Author:  Kento87 [ Mon Mar 28, 2005 4:11 pm ]
Post subject: 

SO would the PSI/HP gain be just for our little motors or all in general?

So if you have 200 Base HP and run 5PSI you would gain 68 HP? man that would be an awsome HP per $ gain.

Author:  Bigbearzuke [ Mon Mar 28, 2005 5:11 pm ]
Post subject: 

Kento87 wrote:
SO would the PSI/HP gain be just for our little motors or all in general?

So if you have 200 Base HP and run 5PSI you would gain 68 HP? man that would be an awsome HP per $ gain.


in theory yes. If your turbo is large enough or has enough CFM/flow it should technically make that much power. This equation assumes your base CFM paramiters are met. On a GTi motor the base CFM of the motor is 148 CFM and at 15 PSI the boost airflow rate would be around 299 CFM

If your V8 meets this requirement then in theory it should make the 68 HP

Author:  Kento87 [ Mon Mar 28, 2005 5:37 pm ]
Post subject: 

Bigbearzuke wrote:
Kento87 wrote:
SO would the PSI/HP gain be just for our little motors or all in general?

So if you have 200 Base HP and run 5PSI you would gain 68 HP? man that would be an awsome HP per $ gain.


in theory yes. If your turbo is large enough or has enough CFM/flow it should technically make that much power. This equation assumes your base CFM paramiters are met. On a GTi motor the base CFM of the motor is 148 CFM and at 15 PSI the boost airflow rate would be around 299 CFM

If your V8 meets this requirement then in theory it should make the 68 HP


That is sweet and what makes you think it for my V8???? :lol: I want to set up a 3 cyl with 20 lbs boost and llok at their faces when I toast a $25k mustang with a $500 Sprint :twisted:

Author:  Bigbearzuke [ Mon Mar 28, 2005 6:43 pm ]
Post subject: 

Kento87 wrote:
That is sweet and what makes you think it for my V8???? :lol: I want to set up a 3 cyl with 20 lbs boost and llok at their faces when I toast a $25k mustang with a $500 Sprint :twisted:


I would need to know your bore and stroke for the Caddy motor. BTW are you using a bubbajoe kit? I had one in my Fiero years and years ago. Just email me the info so we don't waste space on non-Suzuki based chat ;)

For the T3, the base CFM is 92 CFM and @ 20 PSI of boost you require a turbo flowing 217 CFM to make 149 HP. The RHB3's don't flow that much air and I believe the HP tops out @ 125 +/- HP

Author:  Gasoline Fumes [ Tue Mar 29, 2005 4:00 am ]
Post subject: 

I think I fixed the charts, but somebody should check to see if I got all the numbers right. :D

--table code removed since HTML is no longer supported--

Author:  Kento87 [ Tue Jun 21, 2005 2:27 pm ]
Post subject: 

Bigbearzuke wrote:
For the T3, the base CFM is 92 CFM and @ 20 PSI of boost you require a turbo flowing 217 CFM to make 149 HP. The RHB3's don't flow that much air and I believe the HP tops out @ 125 +/- HP


So with a Larger Turbo, say a K14, what would the HP yeild be? Im crappy with math even if I have the charts.

And no I did my own 4.9 mounts.

Author:  accent1 [ Sat Aug 05, 2006 4:41 pm ]
Post subject: 

Ok so why does my Hyundai stay together?

Here's the set up

1.5 SOHC 7.5 to 1 comp 3 valve per cyl

super unleaded fuel thats 93 octain I think

18 to 20 PSI with NO timing retard thats 32 deg total timing when into the boost!

Oh yea NO detonation. :?

I duno but thats what it is!

accent1

Author:  Devil-GTi [ Sun Aug 06, 2006 1:44 pm ]
Post subject: 

compression ratio :wink: stock gti bottom = 10 to 1
yours is 7.5 to 1
that changes allot
is your car factory turbo?

Author:  accent1 [ Sun Aug 06, 2006 9:53 pm ]
Post subject: 

nope I ran 15 psi with no boost retard on the stock internals thats 10.5 to 1 comp.

I put the 7.5 to 1 in there later!

Oh and that was a no she was not turbo from the factory! :D

accent1

Author:  stevieh6 [ Tue Aug 07, 2007 4:50 am ]
Post subject: 

you base your info on stock timing, can you state what the stock timing is please

Author:  swift13b [ Sun Dec 09, 2007 7:11 am ]
Post subject: 

6 is the typical number I seem to see floating around

Author:  mitzoplix [ Tue Mar 15, 2011 11:07 pm ]
Post subject:  Re: Turbo theory: fuel and timing requirements

i just bought a 1993 geo metro hatchback and im looking to turbo charge found a kit with a t3t4 turbo is that a good turbo to go with to push alot of horsepower im looking to put it on the stock motor first and run about 7psi to10 amd come back later with forged pistons amd maybe alittle 50shot of nos tell me what do yall think oh yea..and i only bought her for 400 smackers with 150k miles 8) oh and forgot to say it has the 3cyl with the 5 speed also looking at a stage 3 racing clutch to go in it to

Author:  Solerpower [ Sun Aug 23, 2015 11:49 am ]
Post subject:  Re: Turbo theory: fuel and timing requirements

mitzoplix wrote:
i just bought a 1993 geo metro hatchback and im looking to turbo charge found a kit with a t3t4 turbo is that a good turbo to go with to push alot of horsepower im looking to put it on the stock motor first and run about 7psi to10 amd come back later with forged pistons amd maybe alittle 50shot of nos tell me what do yall think oh yea..and i only bought her for 400 smackers with 150k miles 8) oh and forgot to say it has the 3cyl with the 5 speed also looking at a stage 3 racing clutch to go in it to


Saying I bought a t3t4 turbo does not in any way narrow down the specifications for the turbo enough to make an informed decision on the match of a G10 engine to it. The T3 flange and turbine housing do not all have the same turbine diameter or A/R. Typically the T4 hybrid wheels (cold side) are larger than just one off a T3-50, T3-60, and T3-Super 60. That being said the non-hybrid wheel of say a T3-60 are too large for a G10's air flow rate. In general you could use a T3-60 for a G13B, but they would not be a good fit for a G10. Find the turbine diameter inducer and exducer, and wheel diameter inducer and exducer and the A/R for both hot and cold and then you could begin to have a better idea of what your asking for.

Or, I can just tell you that in most likely hood that no it won't be a good match.

Crap I just responded to a post from 2011

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