JETS3T8

Nope. Motor was running perfectly fine.
Seals/springs/bearings/compression were in excellent condition. Only noticeable issue was rotor contact with the irons, wasn’t bad at all, just some discoloration.I’ve added 1/2” studs, race clearanced the sides/tips/pockets and lightened the rotors. Also running front & rear ball bearing stationary gear supports from E&J now.

Anyway, with a little help from the new guy on the right, the Reni should easily make over 800+whp

TeamRX8

iTrader: (25)

which model is that?

JETS3T8

G45-1500 w/ 1.44 A/R T4 Divided

TeamRX8

iTrader: (25)

w👀t - w👀t
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TeamRX8

iTrader: (25)

out with the old, in with the new

billet engine now, changing to a dual compound turbo setup

also changed the accounts from landspeedrx8 to landspeedrotary




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Brettus

iTrader: (2)

Yeah ...pretty impressive. Seems the Renesis plans have been put to bed ?

neit_jnf

I wonder why some compound builds only cool one stage of the system instead of both...
I'm sure cooling both must come with its benefits!

TeamRX8

iTrader: (25)

100% methanol fuel and limited WOT run time. Even from a dead stop, a landspeed run might only last 35 - 60 seconds depending on the course length from dead start to crossing the speed trap finish lights.

200 mph is ~18.0 sec/mile
250 mph is ~14.4 sec/mile

the previous huge single turbo had no intercooler, compound will have more heat buildup with double compression.
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MilosB

also drawbacks.
for alcohol fuels, some have found issues if intake is to cool to evaporate it for combustion.

@TeamRX8 less heat than single compression event for same mass flow.

TeamRX8

iTrader: (25)

you sound pretty sure of yourself again …
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TeamRX8

iTrader: (25)

as is often the case in the read-something-on-the-internet generation, most people don’t understand how methanol fuel really works, as well they believe they do. The AFR enrichment process is especially not well understood:

https://racecarbook.com/tips/turboch...methanol-info/


start at time mark 15:00 for compound turbo system explanation



dual compound turbo on an SR20 4-cyl



^^which btw, potentially my future tuner under consideration if a MoTeC ecu is purchased, Maxworx is presently developing a triple compound turbo system for this engine now …
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TeamRX8

iTrader: (25)

this was maybe more appropriate, but only 6 sec drag run time



and just pointing this out to trigger the usual internet experts into boldly driving off the cliff again

it reminds me of the guy who stated on here not so long ago, “I see they figured you out over on RX7Club now too”. 🤣
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MilosB

it pretty simple @TeamRX8 , a heat buildup in a compression of the intake charge is directly in proportion to the efficiency of the turbocharger at that PR and at that mass flow.

we can calculate the PR based on assumption of 9000rpm, 1.3L and 2kg/s (probably even more) of air to make 2000hp (and disregarding the heating of the air for simplicity of calcs, but if you really want I can add that in to calcs as well)

some simple math, 9000rpm=150rps=> 150x1.3L=200L/s intake volume capacity
we need to intake 2kg/s = 1640L at atmo pressure.

that gives volume ratio which is equal to pressure ratio (PR) of roughly 8:1 , I don't know of any turbine capable of running in the high efficiency on such PR.. but if we split it in to two sections, we only need to compress two times at PR of 2.8 which is right on the sweet spot of "any compressor".

If we would have a situation of running two 100% efficient compressors, the heat in the intake would be same between the two combos

lets do a little math but lets set first some physics in content:T2 = T1 * (P2 / P1)^((γ – 1) / γ)

In this formula:

• T2 represents the temperature of the compressed air, typically in °C or °F.
• T1 is the initial temperature of the ambient air.
• P2 is the final pressure of the compressed air.
• P1 is the initial pressure of the ambient air.
• γ (gamma) is the specific heat ratio, which is a dimensionless constant representing the ratio of specific heats (Cp/Cv) of the air. The specific heat ratio (γ) varies depending on the type of gas or air being compressed. For dry air, γ is approximately 1.4.

from the above we can say
T2 = T1 * (P2 / P1)^0.4
for single turbo the above formula takes place,
while for compound, assuming equal share of "work" where P1.5 is the intermediate pressure point
T2 = T1 * (P1.5 / P1)^0.4*(P2 / P1.5)^0.4 , where (P1.5 / P1) and (P2 / P1.5) are equal and the product of the two is equal to the P2/P1.. meaning (P1.5 / P1)=(P2 / P1)^0.5 ; (P2 / P1.5)=(P2 / P1)^0.5
some further math:
T2 = T1 * ((P2 / P1)^0.5)^0.4*((P2 / P1)^0.5)^0.4=T1*(P2 / P1)^(0.5*0.4)*(P2 / P1)^(0.5*0.4)=T1*(P2 / P1)^0.4

some further math reminder bellow:
Product Rule am × an = am+n
Quotient Rule am/an = am-n
Negative Exponents Rule a-m = 1/am; (a/b)-m = (b/a)m
Power of a Power Rule (am)n = amn


PR of 5 is the highest I have ever seen on ANY compressor map and it in this link.. but I'm novice so there might be an a turbo with PR of 8 in single stage but probably not even near the compression efficiency of a "low" 2.8 PR...
https://www.garrettmotion.com/news/n...bo-any-engine/

TeamRX8

iTrader: (25)

I’m not claiming expertise either

that above is undeniable in a sense, except imo you fail to perceive the difference between the more common compound setup of diesel fuel that doesn't pre-detonate vs fuels that do.

maybe go back to the methanol fuel link that was provided and review again

the operating rpm range also playing into it, most landspeed vehicles don’t launch from a dead stop on their own, but are either pulled/pushed by another vehicle up to a speed where they can finally operate from in the lowest gear ratio. From there this RX8 has a 6-spd short ratio transmission gearset to hold a tight rpm powerband.
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TeamRX8

iTrader: (25)

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