rorrazo18

iTrader: (1)

Hey everyone, i have a built type A block half bridge, pinned, balanced, clearenced with mazda oem apex seals that according to sean at aspec can do 700 hp no problem. But now im told by several people that it can crack at those power levels and an A code block will not hold. Also now that aspec is closed, i cant get anybody to warranty me a build on this block. So im looking for more accurate opinions from all you guys with great experience and reaching out to see what options i have.

rx7jocke

the awnser to your question is maybe and it depend

for the street it probably would if you havea a good tune and drive sort of carefully, but for the racetrack no way, i am building a 550-600hp 20b for the racetrack and was recommended the following:
Streetport (noice issues at teh racetracks so we have a 95db limit in sweden :-S)
Fully pinned
Race bearings
fully clearenced
balanced assembly
balanced and weightened rotors
more oilpreassure with external oilfilters (yes dual assembly)
external oilfeeds to the bearings
internal oil mods
internal watermods and external watercooling lines to the spark plug areas
baffeled oilsump
balanced clutch and flywheel
electric waterpump
excessive LIM

this was teh bare minimum for a TRACK driven 20b with that hp rating(100-150 less then yours) according to my builder, drysump and lightened rotors and ianetti seals was the things i skipped...

Your dowell lands might be fine if your tune is good and so on and no ninja dragracing starts with drag radials are made but there are other problems with the 20b.
1. Heat (manageble for a streetcar but devastating for a track car) thats why i have the oil and watermods
2. Balance, The 20b are harder to get balanced in a good way then a 13b where the 2 rotors help cancel eachother, so if you intend to drive it hard and rev alot you have to know everything is balanced well, my engine is rated to -9.5k IF the oilpreasure dont drop (no drysump remember) but i will have the revlimiter at 8k or wherever the dyno says the power starts falling.

there are many ways to skin a cat and this is my way (well my builders way) and he is known for building engines that last and delivers. You dont want to take stupid chances with an engine that cost 20k usd just for the block.....

rorrazo18

iTrader: (1)

Yes your absolutely right. And wich is why im trying to do as much reasearch as i can. So im sure im doing the right thing. Now that theres just so much different opinions , its hard to know whos right. But if i can get someone to warranty me a build with this engine, i might go ahead and do it. Im half way there but just too many people expressing concern on the block.

racingdriver

I have road raced my 20b turbo at 700 plus hp since 2007. I have run races as long as 60 minutes. You don't need to do anything to the motor!!!! The only way you will break it is a bad tune or an accessory failure: over boost, failed injector, etc. Having said that eventually you will crack the side plates. It starts small but the plates cant handle the power that well.

You will get about 50 hours of hard racing out of it and then you will need new apex and side seals. The seals will chatter and u may also need housings at that time.

After 8 years of learning this set up we speak the truth.

Monsterbox

iTrader: (6)

Thanks for your comments that's great to know. Makes me certainly feel better about 700hp. I have no mods to the engine besides porting and D series. Can you please tell us what series engine you have?

Can you expand on what you mean by eventually crack the side plates? So have you cracked the plates yet within the 50 hrs, or within the 8 years? Seems slightly contradicting argument, not necessary to touch the motor, yet the plates will eventually cracks. If its made it 8 yrs without cracking it sounds pretty trustworthy, but if not, Maybe this could be prevented by the series of motor and/or pinning for a heavy race use engine?

Sobr609

iTrader: (2)

Yes, my pinned A series motor holds over 700hp. I dont run pump gas though

racingdriver

I ve run b, c and d motors. We pinned the first one and it still cracked at 50 hours . Didn't pin the others and have seen the same hairline cracks in the center . They are still usable and didn't affect the engine performance but you never know how reliable it will be through the next 50 hour cycle.

If you are tracking you will need 2 huge oil coolers and a big radiator. Also a huge catch can for oil as without dry sump it will throw some oil out under prolonged boost
and cornering.

The guys at Forcefed Racing in Abbotsford built several street 700 hp 20b rx7 s and have seen 25,000 kms and more and are still going strong. A street car doesn't see the non stop heat, boost, load, sticky slicks, g forces , etc so will last a long time, my guess is about 40-50,000 kms.

Banzai-Racing

iTrader: (11)

I can find no rational reason why any shop would warranty an engine built by another shop. There is no way of knowing what condition the engine is actually in or what parts were used without opening it up and rebuilding it. We will not take the risk of installing an engine from another shop, since we have seen so many substandard rebuilds over the years.

rorrazo18

iTrader: (1)

Yes your absolutely right wich is why im looking for my best option. One is to have sean talk to someone and have him give all details and if possible do it in person with the engine present so it would avoid opening it and rebuilding it again to avoid that paying more. The other option i see is to call different shops to see who i would feel more comfortable with and have them open it and put it together again and go from there. But according to sean at aspec, he only trusts about 4 people in the country in knowing how to put an engine like this together ( type A block, 1k hp capable motor) but than that i dont know. So i will be reaching out to different shops to see whocan give me the best option and deal. Im in chicago by the way.