Hey Guys

I spent a few hours today putting these together. Just thought it'd be helpful to see the three compressors compared to one another. Here are 3 possible combinations.

A note: All of the data was done using Excel. The 3 maps (obtained from the web and from PE Japan directly),were cropped at the 0-14 m^3/min marks on the x-axis, and 0-24 psi (1-2.6 PR) marks on the y-axis (with great care), followed by scaling to to conform to excel's x/y graph. The lines were drawn to represent the flow characteritics of OUR engine at diff. rpms/boost levels.

The data does differ a little from Squill's maps (a my350z.com forum member) - but they are very close.

I did not include the %efficiencies for each of the "envelopes". The PE one is just flat out unknown (though we I have the PE1820's map complete with %-ages, it sure is invalid to make the assumption that they are the same).

The blue is the PE1420 compressor (PE TT Kit), the green is the Garrett bb GT28R turbos, and the green is the Mitsubishi TD05H-18G (Greddy TT kit).

The trick is to operate, at the desired boost level, in the innermost envelope, as that represents the highest compressor efficiency (no actual % for pe available, but the inner most envelope probably represents the 78% efficiency envelope, whereas the greddy inner envelope is 77%).

I know it's hard to see, but look carefully and notice where the envelopes are for each of the turbos.

Gurgen








<P ID="edit"><FONT class="small"><EM>Edited by gurgenpb on 07/29/04 11:04 PM.</EM></FONT></P>

 

BTW, do not pay attention to the smaller size of the gt28r's envelope - that is just an extra definition of the "next" efficiency level.

The more important thing to look at is the location of the "center" of the map, and see if it is achivable in our cars.

These essentially show what I have been talking about before... the efficiency of the PE (and the Garrett) turbos at the lower boost level compared to the Greddy turbos. The PE turbos start off being very efficient (the highlighted 78 or 79% envelope - not sure which, probably 79% according to PE's other plots where they DO identify the 79% envelope) at a much lower boost level (around 3-4psi) while the Greddy turbos reach the 77% efficiency level (not PE's 78-79%) at about 7-8psi.

Of course, here you can also see the advantage of the Greddy turbos over PE ones; the greddy turbos keep their 77% efficiency all the way up to 22psi, whereas PE 78-79% enevelope runs "only" up to the 15 psi. However, the PE 77% (or maybe ven 78%) envelope is the one that is just outside the highlighted envelope, and goes up 18psi. So, 22 psi for Greddy (77% efficiency) and 18 psi for PE (78% efficiency), that's where Greddy will shine. So you decide if you are going to be boosting over 18psi or not, that will allow you to choose the moreappropriate turbo for your car. However, noone has gone over 17psi on this motor - fully built at 3.5L (not overbored) - at which point they developed 556 wheel (around 650 crank hp). That would be enough for me, especially given that PE's (as all BB turbos as compared to sleeve types - accordig to Corky Bell) spool up on average 17% faster.

So, the notion that PE turbos are SMALL is nonsense, they are NOT. They ARE smaller and slightly lighter, than Greddy's, allowing for the characteristics discussed above. They ARE much better fitted for the stock motor (lower boost efficiency) while giving up very little (IMO and for purposes - giving up next to NOTHING) on the top end.

Another reasonably good turbo (reasonably well chosen) is this Garrett one, which from what i heard maybe what the 530BB turbos of the JWT TT kit are based on. However, keep in mind that the small highlighted envelope is a 75% efficiency envelope (unlike Greddy's 77% and PE's yet higher 78-79%). So it seems as though these are not as efficient (if you compare absolute numbers - and I am not entirely sure that that's valid to do) as the PE and greddy turbos. JWT has potential winner, and I will be eagerly awaiting to see it's performance. It's time for more great kits to get onto the market!

G

<P ID="edit"><FONT class="small"><EM>Edited by gurgenpb on 07/29/04 11:50 PM.</EM></FONT></P>

 

dam, good work; i don't know too much about turbos and any info definitely helps. i'm planning on getting the PE system or waiting for the JWT to come out.

 

Hey Guys

I have updated the pictures above, as i identified the comparable efficiencies and highlighted them. I didn't realize this before, but I will have to change my statement on the Garrett GT28R turbos, I didn;t notice that their inner envelope is a 75% efficiency envelope (comapred to Greddy's and PE's 77% and 78% values). Now, yes, that's not a HUGE deal, but one that is worth pointing out.

Also, notice the size of the efficiency envelopes.

Gurgen

 

Gurgen,

Great work on these maps. Keep it up! We are all learning from you.

2003.5 Black 5AT Sedan
z-tube/ jwt popcharger/crawford plenum/crawford cats/
stillen exhaust/grounding kit/e-fans
technosquare ecu /350z thermostat/double din

 

Gurgen,
Can you put those charts in 3D next time?????????????? It would be a lot easier to visualize that way :P







Good job!

Clint (THX723)

 

Wow! Great job man. Thanks for the maps.

'93 Mazda RX-7 Touring
313rwhp 249lb-ft
12.971@111.92

 

Great Post. However, I think it is a bit misleading. Peak compressor efficiencies while important are not the most important factor in choosing a compressor. What also needs to be looked at is the range of efficiency the turbo will see in the motor's powerband. In the PE1420 vs the TD05H-18, you can see this the most clearly. I'll use 12 psi as an example. The TD05's peak efficiency island is close to and partly beyond redline(6500 RPM). In fact it doesn't even hit the 77% efficiency island until about 5700 RPM. It's a bit hard to be certain as the rest of the map is not marked with efficiencies, but down as low as 4000 RPM, I would not be surprised if the efficiency is under 70%. On the other hand the PE turbo at 12 psi maintains at least 77% efficiency from about 4500 RPM almost all the way to redline. By redline it will probably drop to about 76%. That's really insignificant as the drop in efficiency is low and it's for a very short range(looks about 6250 to 6500 RPM). What is really significant though is what is occuring before the peak efficiency is reached. Again, it's hard to say since there are no figures at each island, but I'd guess the that you would not drop into the 60% efficiency range until you werre closer to 3000 RPM. So why is this important? Better efficiency not only creates less heat in the charge air, but it does so because it is more aerodynamic. This means the turbine wheel will need to use less exhaust energy to create the same boost. This means the wastegate can open sooner and bypass more air around the turbine which lowers exhaust backpressure. Less backpressure increases the Volumetric efficiency of the motor. Basically, you get more power in more ways then just a cooler denser charge. And just based on the maps itself, it is fairly evident that the PE turbo is smaller and will spool faster. This should result in a more responsive turbo and a lower boost threshold. The broader range of efficiency will also be a little more forgiving to shifting earlier or coming off a corner at a lower RPM than might be optimal.

Gurgen, I'm not saying in anyway that the info you posted was wrong. I just think the post may mislead others into thinking only of peak efficiencies only and not look at the bigger picture as your posts seemed to have a strong focus on the peak efficiencies.

My personal favorite of these three based on the airflow info you posted would be the PE. There are few that will probably look to boost to levels out of this turbo's peak efficiency ranges and if I were looking to boost that high, I'd look for something that is a much better match than the TD05 or the GT-28R. Especially since the motor will be under much more stress. This is a very well put together post though.

 

You are absolutely correct.

I just thought that the size, i.e. the area, of the envelopes and its significance was self-evident, and I neglected to emphasize that. Therefore, I just proceeded to explain and underline the equal efficiency envelopes in all three compressors, so as to allow for a more "apples-to-apples" comparison. Thanks for pointing out the shortcoming. In spite of this, it does seem that you agree with me nontheless.

As far as choosing the turbos, there are several choices. For me, as I am doing a full motor build, and for this displacement motor, i do believe that the PE1420's are perfectly allright up to 15 psi, and still very acceptable at 18 psi. For this reason, I went with a 9.3:1 static CR pistons. But, if I were doing a stroker kit for this motor and putting on turbos, than the PE 1820's would be my choice.

G

 

I don;t doubt it for a second, that';s waht I have been saying all along. I just wished I dynoed already. Will be dynoing on the first of Sept.

G

 

Awesome, informative post. Thanks so much, just in case you think the lack of replies is indicative of few people reading or appreciating your hard, well thought out post. This is a wealth of info that I will be coming back to as I get closer to FI upgrade time.

 

Glad to help bro. Anytime!