if you were me, how would you go about doing this?
 

Hiya

After reading the size matters thread i thought you guysmight be able to help out a bit

Anyway, ill give you a run down of my plans and let me know what you would go with.

Ok first thing is, im from england, so we dont have dynojets or produce the daft figures you guys produce so that needs to be thought about.

For refence it mentioned 378whp at 1bar of boost on a gt35 with no porting, thats the figures we are getting with porting on our rollers, its not that we are crap tuners, just that our rollers read alot lower over here.

Im running my new engine in at the moment
http://www.rotaryheads.com/porting/i...t-vs-stock.jpg
this is the port thats on it now(reference for size) and also has inlet manifolds, secondary throttle removed, throttlebody ported and exhaust ports done.

I will be running water injection with a large intercooler so inlet temps will be no worries.

the aim of the car is to enter a few events and take a few records.

the power im looking for is around this.
500rwhp at 1bar(500fly for us in uk)
580rwhp at 1.3bar(580fly uk)
630rwhp at 1.6bar(630fly uk) on racefuel

i know thats not an exact numbers but something around that level as ill need 630 on racefuel to break 200mph in 1.6miles at a UK event i want to enter.

for reference i found a streetported t78 did 506flybhp at 1bar in the UK so would i be looking at a gt42 94mm as an equivalent garrett? or maybe even a precision as the supra guys are getting good numbers and boost threshold.

Thanks in advance for your help as ill be interested in what you have to say

If you have any questions at all, ask

Lee

A 42R would do the job, but the 4202 would be a better choice. Another good one would be a Precision 71 or 72mm billet, or even their 76mm billet. A BW S375 would also be good. What sort of budget do you have for a turbo?

T78's Garrett equivalent is a To4R. However as stated you should use the GT4202R, Garrett is phasing out their old cast units with the New Billet GTX lineup, that would be the route to go( GTX)

.

a gtx4202 would be the best route if you ask me, but if you're on a budget, its all about the bw s475!

what sort of price do the s475 go for?

thanks very much, thats brillaint, ill be looking more into the s475 as it seems a really good price, any comparison in spool time compared to the GT42 knocking about anywhere? This is a bit of a budget build and the UK exchange rate isnt great at the moment so any savings will help

The S475 is much larger than a GT42 and will definitely spool slower with the 96mm turbine. The 83mm turbine is very comparable, but would be more considered an S375.

an s475 will react extremely well to a high overlap porting such as a bridge, semi pp, or a pp. but turboR1 have a completely stock engine block with an s475, and hes running a 9.8 something.

guys look on ebay

Depends on which S475 he uses. There are 3 main turbine wheels available, and which one is uses will definitely change the spool characteristics.

I'd advise n the GT-4202 as well. Currently we're making 620 rwhp at 24 psi, which is right around your target at 1.6. This on pump, with less than 300cc's on meth.

Specs are full birdge, GT4202, 1000pri/1600sec, Ebay IC, Power FC

Garrett unit over the BW unit having worked and built cars with both. I prefer the garrett for a few reasons.

and what are those reasons?

hmmm this is good to hear, what do you hit full boost by and what do you rev it to, any info like that would be brilliant, i assume its a bb?

Posted them a few times, weight, parts availability, and very very reliable track record. The BW units offer some better wheel combo's, but I don't like the one piece BP CHRA design and more so I prefer BB units for most apps. Even still I have a S480 here making over 900hp on a drag car, so it's not like I don't use them.

~S~

whats the deal with rebuilding BB turbos at this point? I know i can have a BW turbo fully gone over for a few hundred bucks. are you stuck with buying a new CHRA for BB units still?

Dyno can be found here (first post of page, put up by Jason at Rx7Store), along wtih other info on the setup:

https://www.rx7club.com/auxiliary-injection-173/500-pump-ai-club-628209/page3/

Didn't take it past 7300 rpm as we were running out of fuel... there's room for plenty more though. Conservative tune, spark plugs are 9's, twin power, stock intake manifold and TB (this will be replaced with our custom unit, runners and all.
On the streets boost hits hard at anything above 4 and only pulls harder the faster you go, its a strange feeling.

If I remember correctly, the NEW Precision DBB units can be rebuilt, rather than having to buy a new CHRA.