Jump to content
SAU Community

Recommended Posts

Hey guys is this for real???

I work with a guy who has a rb30 N/A and has told me it runs 14:1 compression and methanol with around 4-500 hp is this possible

Cheers Russ

14 to 1 compression ratio and methanol is entirely possible.

The bhp is questionable, particularly if it is still SOHC.

My guess would be 350 bhp, or thereabouts

:( cheers :(

Link to comment
https://www.sau.com.au/forums/topic/133814-bullst-or-not/#findComment-2480612
Share on other sites

maybe depending on revs?

The problem is the SOHC head doesn’t flow enough air (without boost) to make anywhere near 500 bhp. So using ever increasing RPM (to get more BHP) is not really an option.

:( cheers :(

Link to comment
https://www.sau.com.au/forums/topic/133814-bullst-or-not/#findComment-2480764
Share on other sites

this is on stock head maybe ported?

Nope, that was allowing for MAXIMUM porting. I know what they flow on the flow bench and it is nowhere near 500 bhp worth of airlfow. That's with the biggest (oversized) valves you can fit in the head as well.

:( cheers :(

Link to comment
https://www.sau.com.au/forums/topic/133814-bullst-or-not/#findComment-2480826
Share on other sites

rather than starting another thread, i'll just hi-jack this one :D

on the topic of porting heads on NA engines, i got to thinking, i was reading the other day about volumetric efficiency and it was basically that a 100% effecient engine could only draw in its own capacity worth of air. e.g. an RB30 could only suck in 3 liters of air. this article also said that most engine these days are very effiecent, like well into the 90% region.

now heres my question, if they are so effiecent, how does porting heads help? if it already fills the cylender to 90 something percent, and you port it, will that increase of a couple of percent in efficiency make a big diference to power output?

Link to comment
https://www.sau.com.au/forums/topic/133814-bullst-or-not/#findComment-2487043
Share on other sites

rather than starting another thread, i'll just hi-jack this one :cool:

on the topic of porting heads on NA engines, i got to thinking, i was reading the other day about volumetric efficiency and it was basically that a 100% effecient engine could only draw in its own capacity worth of air. e.g. an RB30 could only suck in 3 liters of air. this article also said that most engine these days are very effiecent, like well into the 90% region.

now heres my question, if they are so effiecent, how does porting heads help? if it already fills the cylender to 90 something percent, and you port it, will that increase of a couple of percent in efficiency make a big diference to power output?

Ref italics: Not true- Due to the nature of high-speed airflow (air is actually a gaseous liquid), the chamber of an engine designed/modified for high rev efficency (increased cam duration/overlap, head porting, inlet manifolding etc) will acheive greater than 100% VE as the intake air continues to ram into the cylinder due to inertia, after the the piston has passed BDC.

Even old OHV 2-valve engines can easlily achieve 110-115% VE when suitably modified for racing. I don't have the figures, but I suspect an F1 engine would be a bit higher again.

Link to comment
https://www.sau.com.au/forums/topic/133814-bullst-or-not/#findComment-2487997
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Latest Posts

    • My dream is also to have a proper hoist, but I don't think it will ever happen. My quickjack is probably as close as I'll ever get, it really is very good though. 
    • Yeah we keep on in the dailies, it is pretty poor how many animals get hit and the driver leaves without checking....have saved a couple of little ones over the years. Bit of a gruesome job though, pouches generally need to be cut open because they are so tight and often the joey doesn't realise mum is gone so they are still locked onto the teat. I checked the modules in front of the DS wheel where an oil cooler should go.... There is the radar unit - that can go for race use) One of the 2 HX water pumps, the silver cylinder. That needs to be kept but might be able to be relocated But the bad news, the big computer mounted vertically in front of the wheel (blocking any potential air exit) is the electric steering computer. That is required until/unless i do a hydraulic steering conversion, and in CAD based modern car design it is not like I can just pop a big unit like that somewhere else (plus the loom would be too short anywhere else too). So, the passenger side is OK to clear out (just use a smaller washer reservoir, potentially elsewhere), but the DS no beuno
    • Well, all the best with the new camry It was interesting to hear about the UK process, it is generally a lot more streamlined here with a shipping agent looking after all the import side (noting the exact final price can still be a surprise.....) and I've used a few different brokers on the japan (or US) side, and never had any trouble with any of them....luck of the draw I guess. You mentioned you didn't get the auction sheet (understandable since you bought it from a dealer, not auction), but I always try and get hold of that because they are pretty thorough. I've imported 2x R grade vehicles over the years and both were fine, repairs in Japan are pretty thorough compared to here in Oz.
    • BTW I measured the jack I have, it is 70mm at the saddle but you only have about 700 until it returns to 150mm high at the cylinder so it is good but no magic bullet.
    • My experience with Rising Sun Exports Before agreeing to the sale I tried to do as much research as I could (obviously), his Facebook reviews are 98% and he goes Live at least once or twice a week. I contacted 2 people in the UK who had used him for their imports, both had positive feedback. His explanation and talk through of the import process was thorough, answering any query no matter how stupid it was. It felt as soon as the money was sent, communication dropped off. I asked for shipping updates every 2 weeks or so, not wanting to pester him, he never had any updates. I wasn't informed the car had been dropped off at the port, I only found out by his Facebook story. I asked for the photos taken at the port, knowing he would need some for insurance purposes. I received a few 5 second clips and that's it. When asked again, he said his staff had them. Weeks later I asked again, he tells me he doesn't have any, but does have 50 photos from the original advert. I never received them. I eventually got the documents sent via WhatsApp after I mentioned the port was requesting them. I purchased a CarVX report, to find out the vehicle is a Grade R with recorded accident damage, first recorded in 2017 when it was first auctioned. He never told me the grade, then again I didn't ask. His response was "Grade R means nothing, it wasn't chassis damage". Still, I would have liked to have been informed about it. Jon prides himself on being open and honest when it comes to inspecting cars, it's his main job doing so at the auctions for customers. When the vehicle arrived in the UK I noticed a few little cosmetic issues. It's a 21 year old car so it wasn't going to be mint condition. The side skirts are cracked on each corner and the sealant is failing. The front grill on the bonnet/hood isn't secured very well, mounting studs are missing. Both minor things, but again, it would have been nice to be told. During a Facebook Live walk around video of the vehicle, he mentioned it has a front Whiteline anti roll bar/sway bar. While on the inspection ramp, I noticed the stock item has been installed. When first questioned, his response was "the ARB? Switched? Since when, it never had them". Since sending video and photo evidence I've not received a response. I'm probably being over critical of the overall condition of an old car, but all I wanted was honesty (which he claims to have). I'm aware I wasn't his only customer, he's busy doing XYZ but other reviews praise him for great communication with regular updates and photos, I felt I didn't receive the same treatment. 
×
×
  • Create New...