Ramian17":1f8wmjhi said:
I don't know the exact stroke, but I do know that it's going to be a 300 for sure. I'm definitely going to be using an intercooler. I'm not sure on the exact compression ratio, but we talked about keeping it low around 8.5 or 9 so that we can turn up the boost. We talked about a custom ground cam duration at .050" is 212/212, lift is .447/.447, LSA is 114. And the cylinder head from my 240 is getting ported and polished so hopefully the do good on that. I will go over there tomorrow and get the exact stroke, cam grind, and compression ratio from the guy. Thanks so much for your help. I would love to have the numbers you are talking about that would be a huge step up from my old girl. Does what I'm telling you sound like it should work and if so which turbo?!?!?! Lol I'm dying to know and get that thing headed my way!!! Thanks again pmuller9.
The cam specs look good. It will work with the stock rocker arms. Just need to increase the spring pressure.
The 212/212 .050" 114 LSA cam will make peak torque around 2500 rpm which is actually a good place for towing.
The 300 still retains plenty of torque below 2000 rpm so no worries.
Just be sure to install the cam advanced with the intake lobe center @ 110* ATDC.
Now for some fun where you get to participate.
I set this turbo calculator with close to your engine specs @ 15 lbs of boost so you can see the airflow load points in the row listed as Corrected Air Flow Rate, lb/min
These are the points that get superimposed on the turbo compressor map to check for the correct turbo match.
http://www.turbos.bwauto.com/aftermarke ... sin=92044&
You can change any parameter including boost.
Starting at 2000 rpm the flow rate is 16.96 lbs/min and at 4500 rpm it is 30.72. round off to 17 and 30.
At the top of the same chart is the compression ratio which is just above 2. One atmosphere of pressure is 14.7 psi at sea level at standard temp. 15 lbs of boost is just over another atmosphere added. So (14.7 + 15)/14.7 = 2.02 or the ratio of boost over pressure at sea level.
Next look at the compressor map for the GTX2876 that was recommended.
Click on the compressor map image just below the turbocharger image.
https://www.extremepsi.com/store/produc ... ctid=31717
If you look at the left side of the map you will see the pressure level. We will be using a level of 2
Now come across that level till you find the two airflow point of 17 and 30. The load line will be a line between those two points.
Notice that our load line fits nicely across the map with a little extra room to the right for extra power.
It take approximately 1 lb of air per min to make 10 horsepower so 30 lbs per min is about 300 hp.
There is room at that pressure level to go out to 40 lbs per min for 400 hp which gives a good margin for additional HP.
Now change the boost to 5 lbs and use the new pressure ratio and flow points see if the load line is still within the compressor limits.
Looks like a good match?
If you look at the compressor specs it shows the GTX2876 as a 50mm compressor inducer (the inlet or small inside diameter of the wheel) and an 67mm exducer (outside wheel diameter).
Here is the latest Garrett catalog where you can find the compressor map for the GTX 3076 that was also suggested.
You may find that the 3076 is on the large size for your engine application.
https://www.turbobygarrett.com/turbobyg ... -Vol-6.pdf
The GTX series has a ceramic ball bearing center and many other features that causes it to also come with a nice price tag.
From the maps that I could find the Turbonetics T04E 60 trim looks to be on the large side.
The problem is when you are trying to get good boost at low rpm the airflow is low at that point and the load line pushes the surge limit/ left side of the map.
A 360* journal bearing center turbo has a price tag more in line with budget.
I purposely displayed the Borg Warner turbo of choice for your engine at the bottom of the MatchBot calculator.
The S200SX-E has a very wide map at the lower pressure ratios allowing for wide rpm power bands.
Jegs carries the Borg Warner line.
We didn't discuss turbine housing A/R yet. Will wait until you get handle on the compressor side.