Jump to content
SAU Community

Recommended Posts

Less chat more boost!!

hahaha, yeah. I will do that after I upgrade headbolts.

Yeah it will make a difference, it's called more lag with longer duration cams :)

Is that actually always true? Wouldn't longer duration exhaust cam let out more exhaust flow to spool the turbo faster? Or would having more duration intake and more duration exhaust just equal out and have me where I currently sit as far as lag is concerned?

Yes, always true.

Your essentially shifting the motor's efficiency to the right.

Whoever recommended you longer duration cams for response should go read a few text books and educate themselves (saying that very nicely).

You want some more response, I suggest going to a twin scroll setup, ie divided housing, proper twin scroll manifold, twin gates.

Yes, always true.

Your essentially shifting the motor's efficiency to the right.

Whoever recommended you longer duration cams for response should go read a few text books and educate themselves (saying that very nicely).

You want some more response, I suggest going to a twin scroll setup, ie divided housing, proper twin scroll manifold, twin gates.

No one recommended me longer duration for response. I bought the cams before going single turbo. So I have them to put in still. Looks like I'll be looking for a twin scroll setup in the future...or stroker kit lol

No one recommended me longer duration for response. I bought the cams before going single turbo. So I have them to put in still. Looks like I'll be looking for a twin scroll setup in the future...or stroker kit lol

Put the cams in and boost it. Get that face stretch going.

I saw your dyno.

I'm on Tomei Poncam A's with the 260 duration intake and 252 duration exhaust on a stroker motor with divided exhaust housing on BW 8374 EFR IWG .92 housing and I am seeing full boost in 4th gear around 3600 rpms, but full boost in 3rd right at 4k. I'm spinning to 8k rpms and 17 psi is 464 whp and 371 ft-lbs toqrue.If you look at Tomei's website about their stroker kit, my horsepower numbers follow their dyno almost exactly with a 20% addition in power (converting to flywheel from wheel HP). If you notice, there appears to be about a 400 rpm shift to the left from going to a stroker with a bit more top end due to increased displacement.

I'd say your numbers are on target to be honest. We both need to apply more boost and/or move to E85 (which will definitely be my next step - give me a couple of months). I'm still trying for 500 whp on pump gas which should be possible up around 19-20 psi and I would bet it would hit 400 wtq there as well.

Also it should be noted that if I were to go for total streetable HP ON 93 PUMPGAS on a RB26 with stock cams, I would go smaller than 62mm turbo chargers - I would pick something in the high 50mm...like BW 7670 or in your case 5862. These will all have a better powerband and will make the car more usable on the street if less than 20 psi boost. The 7670 would be insanely fast and responsive. I was going to go there, but when the stroker decision was made, i scrapped it for 8374. Again, you'll be limited to 8k or less rpms and likely 20 psi or less, but you'll have better powerband for sure.

I have attached my graph, I'd like to compare the two if you have a printout of yours (or could put it in the attached excel spreadsheet).

 

dyno converted.JPG

dyno converted.xlsx

Tomei stroker information.JPG

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


  • Similar Content

  • Latest Posts

    • Get an inspection camera up there. 
    • Yeah, but look at the margin in viscosity between the 40 and the 60 at 125°C. It is not very large. It is the difference between 7 and 11 cP. Compare that to the viscosity at only 90°C. The viscosity axis is logarithmic. The numbers at 90 are ~15 and ~35. That is about half for the 40 wt oil and <half for the 60. You give up viscosity EXPONENTIALLY as temperature rises. Literally. That is why I declare thicker oil to be a bandaid, and a brittle one at that. Keep the oil temperature under about 110°C and you should be better off.   Having said all of that, which remains true as a general principle, if you have indeed lost enough oil from the sump that the pump was seeing slightly aerated oil, then all bets are off. That would of course cause oil pressure to collapse. And 35 psi is a collapse given what you were doing to the engine. Especially if the oil was that hot and viscosity had also collapsed. And I would put money on rod or main bearings being the source of the any noise that registered as knock. Hydraulic lifters should be able to cope with the hotter oil and lower pressure enough to prvent too much high frequency noise, although I am willing to admit it could be the source.
    • Thanks for the reply mate. Well I really hope its a hose then not engine out job
    • But.... the reason I want to run a 60 weight is so at 125C it has the same viscosity as a 40 weight at 100C. That's the whole reason. If the viscosity changes that much to drop oil pressure from 73psi to 36psi then that's another reason I should be running an oil that mimics the 40 weight at 100C. I have datalogs from the dyno with the oil pressure hitting 73psi at full throttle/high RPM. At the dyno the oil temp was around 100-105C. The pump has a 70psi internal relief spring. It will never go/can't go above 70psi. The GM recommendation of 6psi per 1000rpm is well under that... The oil sensor for logging in LS's is at the valley plate at the back of  the block/rear of where the heads are near the firewall. It's also where the knock sensors are which are notable for 'false knock'. I'm hoping I just didn't have enough oil up top causing some chatter instead of rods being sad (big hopium/copium I know) LS's definitely heat up the oil more than RB's do, the stock vettes for example will hit 300F(150C) in a lap or two and happily track for years and years. This is the same oil cooler that I had when I was in RB land, being the Setrab 25 row oil cooler HEL thing. I did think about putting a fan in there to pull air out more, though I don't know if that will actually help in huge load situations with lots of speed. I think when I had the auto cooler. The leak is where the block runs to the oil cooler lines, the OEM/Dash oil pressure sender is connected at that junction and is what broke. I'm actually quite curious to see how much oil in total capacity is actually left in the engine. As it currently stands I'm waiting on that bush to adapt the sender to it. The sump is still full (?) of oil and the lines and accusump have been drained, but the filter and block are off. I suspect there's maybe less than 1/2 the total capacity there should be in there. I have noticed in the past that topping up oil has improved oil pressure, as reported by the dash sensor. This is all extremely sketchy hence wanting to get it sorted out lol.
×
×
  • Create New...